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Theorem 3.1 Suppose that \( X \) is a statistical FU-space. Then any subset of \( X \) is a statistical FU-subspace.
Proof Assume that \( Y \) is a nonempty subset of \( X \), and \( A \) is any subset of \( Y \) . Then \( {\bar{A}}^{Y} = Y \cap {\bar{A}}^{X} \) . For any \( x \in {\bar{A}}^{Y} \), it is clear that \( x \in {\bar{A}}^{X} \) . Since \( X \) is a statistical FU-space, there is a sequence in \( A \) statistically conver...
No
Theorem 3.2 Let \( X \) be a statistical FU-space, and \( f \) be a pseudo-open mapping from \( X \) onto a space \( Y \) . Then \( Y \) is a statistical FU-space.
Proof Suppose that \( A \) is an arbitrary subset of \( Y \) and \( y \in \bar{A} \) . If \( {f}^{-1}\left( y\right) \cap \overline{{f}^{-1}\left( A\right) } = \varnothing \) , then \( {f}^{-1}\left( y\right) \subset X \smallsetminus \overline{{f}^{-1}\left( A\right) } \) . Since \( f \) is pseudo-open, then\n\n\[ y \i...
Yes
Theorem 3.3 If every subspace of a space \( X \) is s-sequential, then \( X \) is a statistical FU-space.
Proof Suppose that \( A \) is a subset of \( X \) and \( x \in \bar{A} \) . If \( x \in A \), then put \( {x}_{n} = x \) for every \( n \in \mathbb{N} \) . Thus the sequence \( {\left( {x}_{n}\right) }_{n \in \mathbb{N}} \subset A \) converges to \( x \), and hence it is obvious that \( {\left( {x}_{n}\right) }_{n \in ...
Yes
Theorem 3.4 Let \( X \) be a Hausdorff statistical FU-space. If \( W \) is a weak neighborhood of \( {x}_{0} \in X \), then \( {x}_{0} \in {W}^{ \circ } \) .
Proof Suppose that \( \mathcal{P} = \mathop{\bigcup }\limits_{{x \in X}}{\mathcal{P}}_{x} \) is a weak base for the space \( X \), and then there exists \( P \in {\mathcal{P}}_{{x}_{0}} \) such that \( P \subset W \) . If\n\n\[ \n{x}_{0} \in X \smallsetminus {W}^{ \circ } \subset X \smallsetminus {P}^{ \circ } = \overl...
Yes
Theorem 2.1 Every graph with \( m \) edges admits a bipartition \( \left( {{V}_{1},{V}_{2}}\right) \) such that\n\n(i) \( e\left( {{V}_{1},{V}_{2}}\right) \geq \frac{m}{2} + \frac{1}{4}h\left( m\right) \) ; and\n\n(ii) \( e\left( {V}_{i}\right) \leq \frac{m}{4} + \frac{1}{8}h\left( m\right) \) for \( i = 1,2 \) .
The bounds in (i) and (ii) are (individually) tight, and the complete graphs \( {K}_{{2n} + 1} \) are the only extremal graphs (modulo isolated vertices). To prove the conclusion, the authors first take a bipartition \( \left( {{V}_{1},{V}_{2}}\right) \) satisfying (i) (such a bipartition does exist following Edwards’ ...
Yes
Does every graph \( G \) with \( m \) edges have a partition of \( V\left( G\right) \) into \( {V}_{1},{V}_{2},\cdots ,{V}_{k} \) such that both (1.2) and (2.1) hold?
Xu and Yu, by extending and refining the technique used by Bollobás and Scott in [12], proved the following result that affirmatively answers Problem 2.1 up to \( O\left( k\right) \).
No
Theorem 2.3 \( {}^{\left\lbrack {27}\right\rbrack } \) Let \( k \geq 2 \) be an integer, and \( G \) be a graph with \( m \) edges. Then \( V\left( G\right) \) admits a partition \( \left( {{V}_{1},{V}_{2},\cdots ,{V}_{k}}\right) \) such that\n\n(i) for each \( i \in \{ 1,2,\cdots, k - 1\} \) and for every \( x \in {V}...
By the integrity of \( e\left( {{V}_{1},{V}_{2},\cdots ,{V}_{k}}\right) \), Theorem 2.3 provides an affirmative answer to Problem 2.1 for some values of \( m \) .
No
Theorem 3.1 \( {}^{\left\lbrack {66}\right\rbrack } \) Let \( G \) be a graph with \( m \) edges, and let \( M \) be a maximum matching of \( G \) . Then \( G \) admits a bisection of size at least \( \frac{m}{2} + \frac{\left| M\right| }{2} \) .
Proof Let \( M = \left\{ {{e}_{1},{e}_{2},\cdots ,{e}_{r}}\right\} \) be a maximum matching of \( G \), and let \( \left( {{V}_{1},{V}_{2}}\right) \) be a balanced bipartition of \( G \) such that \( {e}_{i} \) has one end in \( {V}_{1} \) and the other in \( {V}_{2} \) for each \( i \in \) \( \{ 1,2,\cdots, r\} \), an...
Yes
Is it possible to remove the tail term \( o\left( m\right) \) in Theorem 3.3?
If the answer is YES, the bound will be sharp as evidenced by the complete bipartite graph \( {K}_{{2k} + 1, n} \) . Compared with the conclusion that graphs with large partitions have good judicious \( {\text{partition}}^{\left\lbrack 2\right\rbrack } \), Lee et al. \( {}^{\left\lbrack {40}\right\rbrack } \) also prov...
Yes
Theorem 4. \( {\mathbf{4}}^{\left\lbrack {39}\right\rbrack } \) For each positive integer \( l \), there exists integer \( k\left( l\right) \leq {2}^{11} \cdot 3{l}^{2} \) (resp. \( {k}^{\prime }\left( l\right) \leq {2}^{16}{l}^{2} \) ) such that \( \delta \left( G\right) \geq k\left( l\right) \) (resp. connectivity \(...
In [44], the authors improved the bound \( k\left( l\right) \) to \( k\left( l\right) \leq {2}^{4} \cdot {17}{l}^{2} \) . Kühn and Osthus’ theorem is a step toward to a very hard conjecture of Thomassen [63].
No
Let \( s \) be a positive integer. Is it true that every graph with minimum degree at least \( {2s} + 1 \) admits a bisection \( \left( {S, T}\right) \) such that \( \min \{ \delta \left( {G\left\lbrack S\right\rbrack }\right) ,\delta \left( {G\left\lbrack T\right\rbrack }\right) \} \geq s \) ?
If the answer is YES, then the bound is best possible as evidenced by the complete graph \( {K}_{{2s} + 1} \) . In the following, we say that a bipartition \( \left( {S, T}\right) \) is \( s \) -good if \( \min \{ \delta \left( {G\left\lbrack S\right\rbrack }\right) ,\delta \left( {G\left\lbrack T\right\rbrack }\right)...
No
Lemma 1.2 If \( G \) is a finite cyclic group and \( \varphi \) is a skew-morphism of \( G \) with power function \( \pi \), then\n\n(1) \( \varphi \) fixes \( \operatorname{Ker}\pi \) setwise;\n\n(2) the restriction of \( \varphi \) to \( \operatorname{Ker}\pi \) is a group automorphism of \( \operatorname{Ker}\pi \) ...
Proof A direct calculation shows that \( \varphi \left( {\operatorname{Ker}\pi }\right) \) is a subgroup of \( G \) . While for a finite cyclic group, there is only one subgroup of a given order and hence \( \varphi \left( {\operatorname{Ker}\pi }\right) = \operatorname{Ker}\pi \) . The second result follows directly f...
Yes
Let \( G = {G}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right), H = {H}_{1}^{S} \circ \left( {{H}_{2}^{V} \cup {H}_{3}^{E}}\right) \). If \( {G}_{1} \) and \( {H}_{1} \) are \( A \)-cospectral regular graphs, and \( {G}_{2} = {H}_{2},{G}_{3} = {H}_{3} \), then \( G \) is clearly \( A \)-cospectral with \( H ...
For example, we know from \( \left\lbrack {3,\text{ p. }{127}}\right\rbrack \) that \( {X}_{1} \) and \( {Y}_{1} \) are 4-regular \( A \)-cospectral non-isomorphic mates shown in Fig. 2. (In fact, the graph in \( {H}_{1} \) has an edge \( \left( {1,8}\right) \) that is a common edge of three triangles but the graph in ...
Yes
Let \( G = {G}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right), H = {H}_{1}^{S} \circ \left( {{H}_{2}^{V} \cup {H}_{3}^{E}}\right) \). By Theorem 2.1, we see that if \( {G}_{1} = {H}_{1} \) is regular, \( {G}_{2} \) is \( A \) -cospectral with \( {H}_{2} \) with \( {\Gamma }_{A\left( {G}_{2}\right) }\left( x...
For example, it is know from \( \left\lbrack {{14},\text{ p. }{211}}\right\rbrack \) that \( {X}_{2} \) and \( {Y}_{2} \) are a pair of \( A \) -cospectral graphs shown in Fig. 3. By using MATLAB, we have\n\n\[ \n{\Gamma }_{A\left( {G}_{2}\right) }\left( x\right) = {\Gamma }_{A\left( {H}_{2}\right) }\left( x\right) \n\...
Yes
Theorem 2.2 Let \( {G}_{1} \) be an \( {r}_{1} \) -regular graph with \( {n}_{1} \) vertices and \( {m}_{1} \) edges, \( {G}_{2} \) and \( {G}_{3} \) be respectively two arbitrary graphs on \( {n}_{2} \) and \( {n}_{3} \) vertices. Then \( G = {G}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right) \) has Laplac...
Proof With respect to the partition (6), the Laplacian matrix of \( G \) can be written as \[ L\left( G\right) = \left( \begin{matrix} \left( {{r}_{1} + {n}_{2}}\right) {I}_{{n}_{1}} & - R & - {I}_{{n}_{1}} \otimes {\mathbf{e}}^{\mathrm{T}} & 0 \\ - {R}^{\mathrm{T}} & \left( {2 + {n}_{3}}\right) {I}_{{m}_{1}} & 0 & - {...
Yes
Example 3 Let \( G = {G}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right), H = {H}_{1}^{S} \circ \left( {{H}_{2}^{V} \cup {H}_{3}^{E}}\right) \) . If \( {G}_{1} \) and \( {H}_{1} \) are \( L \) -cospectral regular graphs, and \( {G}_{2} = {H}_{2},{G}_{3} = {H}_{3} \), then \( G \) is \( L \) -cospectral with ...
For example, we take \( {X}_{1} \) and \( {Y}_{1} \) to be the 4-regular graphs in Example 2 (see Fig. 2), then they are also \( L \) -cospectral. Hence, we claim that \( G = {X}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right) \) and \( H = {Y}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right) \) ar...
Yes
Let \( G = {G}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right), H = {H}_{1}^{S} \circ \left( {{H}_{2}^{V} \cup {H}_{3}^{E}}\right) \). By Theorem 2.2, we see that if \( {G}_{1} = {H}_{1},{G}_{2} \) is \( L \) -cospectral with \( {H}_{2} \), and \( {G}_{3} \) is \( L \) -cospectral with \( {H}_{3} \), then \(...
For example, we know from [12, pp. 383-386] that \( {W}_{2} \) is \( L \) -cospectral with \( {Z}_{2} \) and \( {S}_{3} \) is \( L \) - cospectral with \( {T}_{3} \) shown in Fig. 4. Thus we can construct many infinite families of \( L \) -cospectral graphs \( G = {G}_{1}^{S} \circ \left( {{W}_{2}^{V} \cup {S}_{3}^{E}}...
Yes
Example 5 Let \( G = {K}_{{n}_{1}}^{S} \circ \left( {{K}_{{n}_{2}}^{V} \cup {K}_{{n}_{3}}^{E}}\right) \) . We know that\n\n\[ t\left( {K}_{{n}_{1}}\right) = {n}_{1}^{{n}_{1} - 2},\;{\Phi }_{L\left( {K}_{{n}_{2}}\right) }\left( x\right) = x{\left( x - {n}_{2}\right) }^{{n}_{2} - 1},\;{\Phi }_{L\left( {K}_{{n}_{3}}\right...
Hence, by Corollary 2.3 and (20)-(21), we have\n\n\[ t\left( G\right) = t\left( {K}_{{n}_{1}}\right) {2}^{{m}_{1} - {n}_{1} + 1}\mathop{\prod }\limits_{{i = 2}}^{{n}_{2}}{\left( 1 + {\mu }_{i}\left( {K}_{{n}_{2}}\right) \right) }^{{n}_{1}}\mathop{\prod }\limits_{{i = 2}}^{{n}_{3}}{\left( 1 + {\mu }_{i}\left( {K}_{{n}_{...
Yes
Lemma 1.6 Let \( G \) be a finite 2-group. If \( \exp \left( G\right) = 4 \) and \( M\left( G\right) = {44} \), then \( G \) is isomorphic to the following groups: \( {G}_{1},{G}_{2},{G}_{3},{G}_{4},{G}_{5},{G}_{6},{G}_{7},{G}_{8} \) or \( {G}_{9} \) .
Proof If \( G \) is abelian, let \( \left| G\right| = {2}^{t} \) . Then \( {2}^{t - 1} \leq {44} \) by Lemma 1.4. Hence \( t \leq 6 \) and \( \left| G\right| \leq {64} \) . Therefore, \( \left| G\right| = {64} \) . If \( G \) is a nonabelian 2-group with \( \exp \left( G\right) = 4 \) and every \( x \) in \( G \) of or...
Yes
Lemma 1.7 Suppose that \( G \) is a finite 2-group of exponent 8 and order at least 64. Then \( {n}_{8}\left( G\right) \) is divisible by 8 .
Proof Obviously, \( G \) can not be a cyclic group. Let \( A \) and \( B \) be different maximal subgroups of \( G \) . Set \( H = A \cap B \) . Then \( H \) is a normal subgroup of \( G \), and \( G/H \cong {C}_{2} \times {C}_{2} \) . Let \( C \) denote the third maximal subgroup of \( G \) which contains \( H \) . Th...
Yes
Lemma 2.2 Let \( w = \left\lbrack {{a}_{1},{a}_{2},\cdots ,{a}_{n}}\right\rbrack \) and \( {w}^{\prime } = {t}_{i}w = \left\lbrack {{a}_{1}^{\prime },{a}_{2}^{\prime },\cdots ,{a}_{n}^{\prime }}\right\rbrack \) with \( i \in \left\lbrack {0, n}\right\rbrack \) . For any \( j \in \left\lbrack n\right\rbrack \) ,\n\n(1) ...
For any \( a \in \mathbb{Z} \), denote by \( \langle a\rangle \) the unique integer in \( \left\lbrack {{2n} + 1}}\right\rbrack \) satisfying \( a \equiv \langle a\rangle \) (mod \( {2n} + 1). \)
Yes
Theorem 3.1 \( {}^{\left\lbrack 3,8\right\rbrack } \) For any \( i, j \) in \( \mathbb{N} \) with \( j > 0 \), let \( {t}_{i, j} = {t}_{i + j - 1}\cdots {t}_{i + 1}{t}_{i} \) . If \( x \in {\widetilde{C}}_{n} \) and \( i \in \mathbb{Z} \) satisfies \( \left( i\right) x - {2n} - 1 > \left( j\right) x \) for any \( j \in...
\[ \left( k\right) {x}^{\prime \prime } = \left\{ \begin{array}{ll} \left( m\right) x - {2n} - 1, & \text{ if }\langle m\rangle = \langle i\rangle \\ \left( m\right) x + {2n} + 1, & \text{ if }\langle m\rangle = \langle {2n} + 1 - i\rangle \\ \left( m\right) x, & \text{ otherwise. } \end{array}\right. \]
Yes
Proposition 4.1 The set \( {E}_{{42}^{n - 2}1} \) is infinite.
Proof The result follows from the fact that \( \left\{ {\left\lbrack {{2n} + p\left( {{2n} + 1}\right), n + 1, n + 2,\cdots ,{2n} - 1}\right\rbrack \;|\;p \in }\right. \) \( \mathbb{N}\} \subset {E}_{{\mathbf{{42}}}^{\mathrm{n} - \mathbf{2}}\mathbf{1}} \)
Yes
Example 4.1 \( n = 3 \) . By Lemma 3.1, we see that for any \( w \in {\widetilde{C}}_{3}, w \in {E}_{421} \) if and only if \( w \) satisfies the following condition (a):\n\n(a) There exist some pairwise not 6-dual \( {i}_{1},{i}_{2}, k \) in [8] with \( {i}_{1},{i}_{2} \) being both \( w \) -tame heads and \( k \) bei...
We see that the element \( w \in {\widetilde{C}}_{3} \) with the form \( w = \left\lbrack {8 + {7p},4,5}\right\rbrack \), where \( p \in \mathbb{N} \), is the element in \( {E}_{\mathbf{{421}}} \) . This implies that the set \( {E}_{\mathbf{{421}}} \) is infinite.
Yes
Lemma 2.2 Let \( u \) be a smooth solution of the Cauchy problem (0.1)-(0.2). If for some \( B > 0 \), supp \( u\left( t\right) \subseteq \left\lbrack {-B, B}\right\rbrack \), then for all \( \lambda ,\theta \in \mathbb{R} \), we have\n\n\[ \left| {\mathcal{F}\left( {u\left( t\right) }\right) \left( {\lambda + \mathrm{...
Proof Using the Cauchy-Schwarz inequality and (2.1), we have\n\n\[ \left| {\mathcal{F}\left( {u\left( t\right) }\right) \left( {\lambda + \mathrm{i}\theta }\right) }\right| \leq {\int }_{\mathbb{R}}\left| {{\mathrm{e}}^{-\mathrm{i}x\left( {\lambda + \mathrm{i}\theta }\right) }u\left( t\right) \left( x\right) }\right| \...
Yes
Lemma 2.3 Let \( u \in C\left( {\left\lbrack {0, T}\right\rbrack ;{H}^{s}}\right) \left( {s \geq 4}\right) \) be a solution of the Cauchy problem (0.1)-(0.2) and \( B \) as in Theorem 1.2. Then we have\n\n\[ \rho \left( \lambda \right) \preccurlyeq \frac{\sqrt{B}M}{1 + {\lambda }^{4}} \]
Proof Using the Cauchy-Schwarz inequality, we obtain\n\n\[ \mathop{\sup }\limits_{{t \in \mathbb{R}}}{\int }_{\mathbb{R}}\left| {u\left( t\right) \left( x\right) }\right| \mathrm{d}x \leq \sqrt{B}M \]\n\nHence, for all \( t \in I \), we get\n\n\[ \left| {\mathcal{F}\left( {u\left( t\right) }\right) \left( {\lambda }^{\...
Yes
Lemma 2.7 \( {}^{\left\lbrack 1,\text{ Corollary 2.9 }\right\rbrack } \) Let \( k\left( {\theta ,\lambda }\right) = \mathop{\sup }\limits_{{\left| {\lambda }^{\prime }\right| \geq \lambda > 0}}\left| {\phi \left( {{\lambda }^{\prime } + \mathrm{i}\theta }\right) }\right| \) under the assumptions of Lemma 2.6. If \( \th...
\[ k\left( {\theta ,\lambda }\right) \leq 2\widetilde{\rho }\left( \lambda \right) \]
Yes
Lemma 2. \( {8}^{\left\lbrack 3\right\rbrack } \) Let \( t \in I,\phi \left( z\right) = \mathcal{F}\left( {u\left( t\right) }\right) \left( z\right) ,\theta \) be as in Lemma 2.7 and \( \rho \) be as in (2.3). Then for fixed \( \left| {\theta }^{\prime }\right| \leq \left| \theta \right| \), we have
\[ \left| {{\phi }^{\prime }\left( {\lambda - {\lambda }^{\prime } + \mathrm{i}{\theta }^{\prime }}\right) }\right| \preccurlyeq B\left\lbrack {\phi \left( \lambda \right) + \phi \left( {\lambda - {\lambda }^{\prime }}\right) }\right\rbrack \left\lbrack {1 + \left| {\log \rho \left( \lambda \right) }\right| }\right\rbr...
Yes
Theorem 0.2 Let \( \{ {c}_{n}{\} }_{n = 1}^{\infty } \in \) MVBVS in complex sense, and for some \( {\theta }_{1} \in \lbrack 0,\frac{\pi }{2}),\;\{ {c}_{n}\; + \) \( \left. {c}_{-n}\right\} \subset K\left( {\theta }_{1}\right) \) . Then the necessary and sufficient conditions for the uniform convergence of the series ...
\[ \mathop{\lim }\limits_{{n \rightarrow \infty }}n{c}_{n} = 0 \] and \[ \mathop{\sum }\limits_{{n = 1}}^{\infty }\left| {{c}_{n} + {c}_{-n}}\right| < \infty \]
Yes
Theorem 0.5 Given a complex sequence \( {\left\{ {c}_{n}\right\} }_{n = - \infty }^{\infty } \), suppose that both \( {\left\{ {c}_{n}\right\} }_{n = 1}^{\infty } \) and \( \left\{ {{c}_{n} + {c}_{-n}}\right\} \) satisfy Condition (1). Then the necessary and sufficient conditions for uniform convergence of (3) are that
\[ \mathop{\lim }\limits_{{n \rightarrow \infty }}n{c}_{n} = 0 \] (6) and the series \[ \mathop{\sum }\limits_{{n = 1}}^{\infty }\left( {{c}_{n} + {c}_{-n}}\right) \text{ converges. } \] (7)
Yes
Lemma 1.1 For a complex sequence \( \left\{ {a}_{n}\right\} \) and all \( n \), we have\n\n\[ \left| {a}_{n}\right| \leq {2M}{b}_{n} \]
Proof This fundamental lemma appeared in [1] for a real sequence \( \left\{ {a}_{n}\right\} \) . Here for the complex sequence the proof is quite similar. Suppose to the contrary that for some \( n \) we have \( \left| {a}_{n}\right| > {2M}{b}_{n} \) . Then for all \( n < k \leq {2n} \) we obtain from Condition (1) for...
Yes
Lemma 1.3 Let \( f\left( x\right) \) be the sum function of the series (3). If the complex sequence \( \left\{ {c}_{n}\right\} \) satisfies (2) for some \( {\theta }_{0} \in \left\lbrack {0,\frac{\pi }{2}}\right) \), then \( f \in {C}_{2\pi } \) implies (5).
Proof From the expression of \( f\left( x\right) \) we see that\n\n\[ \left| {{c}_{0} + \mathop{\sum }\limits_{{k = 1}}^{\infty }\left( {{c}_{k} + {c}_{-k}}\right) }\right| = \left| {f\left( 0\right) }\right| \leq \parallel f\parallel \]\n\ni.e.,\n\n\[ \left| {\mathop{\sum }\limits_{{k = 1}}^{\infty }\left( {{c}_{k} + ...
Yes
Lemma 1.4 If a complex sequence \( \left\{ {c}_{n}\right\} \) satisfies Condition (1), then \( \mathop{\lim }\limits_{{n \rightarrow \infty }}n{c}_{n} = 0 \) implies that the series (8) converges uniformly.
Without any difference, the proof of this lemma can be copied word by word from \( \lbrack 4, \) Lemma 3] for the positive case.
No
Lemma 1.5 If a complex sequence \( \\left\\{ {c}_{n}\\right\\} \) satisfies Conditions (1),(4) and (5), then\n\n\[ \n\\mathop{\\lim }\\limits_{{n \\rightarrow \\infty }}\\begin{Vmatrix}{f - {S}_{n}\\left( f\\right) }\\end{Vmatrix} = 0 \n\]
Proof Similar to the proof of the following identity (15) under Conditions (4) and (5), we can easily see that the sequence \( \\left\\{ {{S}_{n}\\left( {f, x}\\right) }\\right\\} \) is a Cauchy sequence for each \( x \) and therefore it converges at each \( x \) . So we only need to show that\n\n\[ \n\\mathop{\\lim }\...
Yes
Lemma 2.1 Let \( \left\{ {{c}_{n} + {c}_{-n}}\right\} \) satisfy Condition (1). Then (6) and (7) imply that \( \mathop{\sum }\limits_{{n = 1}}^{\infty }\left( {{c}_{n} + }\right. \) \( \left. {c}_{-n}\right) {\mathrm{e}}^{-\mathrm{i}{nx}} \) convergences uniformly.
Proof Let \( x \in \left( {-\pi ,0}\right) \cup \left( {0,\pi }\right) \), set \( N = \left\lbrack \frac{1}{\left| x\right| }\right\rbrack \) . For any \( m > \max \{ N, n\} \), write \( {}^{ \dagger } \n\n\[ \mathop{\sum }\limits_{{k = n}}^{m}\left( {{c}_{k} + {c}_{-k}}\right) {\mathrm{e}}^{-\mathrm{i}{kx}} = \mathop{...
Yes
Theorem 1.1 If \( T \) is an algebraically quasi-*- \( n \) -paranormal operator, then \( T \) has the SVEP.
Proof Suppose that \( T \) is an algebraically quasi-*- \( n \) -paranormal operator. Then \( p\left( T\right) \) is a quasi- \( * \) - \( n \) -paranormal operator for some nonconstant complex polynomial \( p \), and hence it follows from [13, Theorem 3.2] that \( p\left( T\right) \) has the SVEP. Therefore, \( T \) h...
Yes
Theorem 1.2 If \( T \) is an algebraically quasi-*- \( n \) -paranormal operator, then \( T \) is polaroid.
Proof Let \( \lambda \in \operatorname{iso}\sigma \left( T\right) \), where \( T \) is a quasi-*- \( n \) -paranormal operator. Then \( T \) is a polaroid by [13, Theorem 3.4]. If \( T \) is an algebraically quasi-*- \( n \) -paranormal operator, then \( p\left( T\right) \) is a quasi- \( * \) - \( n \) -paranormal ope...
Yes
Theorem 1.3 Let \( T \) or \( {T}^{ * } \) be an algebraically quasi-*- \( n \) -paranormal operator. Then Weyl’s theorem holds for \( f\left( T\right) \) for every \( f \in H\left( {\sigma \left( T\right) }\right) \) .
Proof From [2, Theorem 2.11], we have that \( T \) is polaroid if and only if \( {T}^{ * } \) is polaroid. We use the fact that if \( T \) is polaroid and \( T \) or \( {T}^{ * } \) has the SVEP then both \( T \) and \( {T}^{ * } \) satisfy Weyl’s theorem in [2, Theorem 3.3]. Suppose that \( T \) or \( {T}^{ * } \) is ...
Yes
Corollary 1.3 Let \( T \) be an algebraically quasi-*- \( n \) -paranormal operator. If \( F \) is an operator commuting with \( T \) and \( {F}^{n} \) has a finite rank for some \( n \in \mathbb{N} \), then Weyl’s theorem holds for \( f\left( T\right) + F \) for every \( f \in H\left( {\sigma \left( T\right) }\right) ...
Proof Suppose that \( T \) is an algebraically quasi-*- \( n \) -paranormal operator. By Corollary 1.2 and Theorem 1.3, we have that \( T \) is isoloid and Weyl’s theorem holds for \( f\left( T\right) \) . Notice that \( T \) is isoloid, then \( f\left( T\right) \) is isoloid. The result stems from [9, Theorem 2.4].
Yes
Theorem 1.4 Let \( T \in B\left( H\right) \). (i) If \( {T}^{ * } \) is an algebraically quasi-*- \( n \) -paranormal operator, then generalized \( \alpha \) -Weyl’s theorem holds for \( T \). (ii) If \( T \) is an algebraically quasi-*- \( n \) -paranormal operator, then generalized \( \alpha \) -Weyl’s theorem holds ...
Since the SVEP for \( T \) entails that generalized Browder’s theorem holds for \( T \) (see [3, Theorem 3.2]), i.e., \( {\sigma }_{\mathrm{{BW}}}\left( T\right) = {\sigma }_{\mathrm{D}}\left( T\right) \), where \( {\sigma }_{\mathrm{D}}\left( T\right) \) denotes the Drazin spectrum, a sufficient condition for an opera...
No
Theorem 1.2 For the continuous operator \( T : X \rightarrow Y \) between Banach spaces, the following are equivalent.\n\n(1) \( T \) is an Lcc operator;\n\n(2) \( T \) carries every limited set to relatively compact subset of \( Y \) ;\n\n(3) For an arbitrary Banach space \( Z \) and every limited operator \( S : Z \r...
Statement The equivalence between (1) and (2) is [18, Theorem 2.1].
No
Corollary 1.1 Every weakly compact operator is DPcc.
Proof Let \( T : X \rightarrow Y \) be a weakly compact operator between Banach spaces \( X \) and \( Y \) . Since \( T \) carries DP sets into relatively compact sets \( {}^{\left\lbrack 1,\text{ p. }{350}\right\rbrack } \), by Theorem 1.1, \( T \) is a DPcc operator.
No
Corollary 1.2 For an operator \( T : X \rightarrow Y \), the following are equivalent.\n\n(1) \( T \) is weakly limited.\n\n(2) For each Banach space \( Z \) and each weakly compact operator \( S : Y \rightarrow Z \), the composition operator \( {ST} \) is relatively compact.\n\n(3) For each weakly compact operator \( ...
Proof \( \;\left( 1\right) \Rightarrow \left( 2\right) \; \) If \( \;T \) is weakly limited and \( S : Y \rightarrow Z \) is DPcc, then \( \;T\left( {B}_{X}\right) \) is a DP set of \( Y \) . By Corollary 1.1, every weakly compact operator is DPcc. By Theorem 1.1, \( S\left( {T\left( {B}_{X}\right) }\right) \) is relat...
Yes
Corollary 1.3 Let \( E \) be a Banach lattice and \( X \) be a Banach space. If \( {E}^{ * } \) is a KB space and \( E \) has the DP property, then each DPcc operator \( T : M \rightarrow X \) is \( M \) -weakly compact.
Proof Let \( T : M \rightarrow X \) be a DPcc operator and let \( \left( {x}_{n}\right) \) be a bounded disjoint sequence in \( E \) . By [1, Theorem 4.59], \( {E}^{ * } \) has an order continuous norm. It follows from [7, Corollary 2.9] that \( {x}_{n}\overset{\mathrm{w}}{ \rightarrow }0 \) . On the other hand, since ...
Yes
Theorem 2.1 For each two Banach spaces \( X \) and \( Y \), if the closed subspace \( M \) of arbitrary operator ideal \( \mathbb{I}\left( {X, Y}\right) \) has the DPrcP, then all evaluation operators \( {\phi }_{x} \) and \( {\psi }_{{y}^{ * }} \) are DPcc.
Proof Since all \( {\phi }_{x} : M \rightarrow Y \) and \( {\psi }_{{y}^{ * }} : M \rightarrow {X}^{ * } \) are bounded linear operators, it is an easy consequence of Theorem 1.3.
Yes
Corollary 2.1 Let \( {X}^{ * } \) have the Schur property and \( {Y}^{* * } \) have the DPrcP. Then \( L\left( {X, Y}\right) \) has the DPrcP.
Proof The mapping \( T \rightarrow {T}^{ * } \) maps \( L\left( {X, Y}\right) \) onto a closed subspace of \( L\left( {{Y}^{ * },{X}^{ * }}\right) \), which has the DPrcP by virtue of Theorem 2.5.
Yes
Theorem 3.2 Let \( E \) and \( F \) be two Banach lattices with \( E \) having the weak DP property. Consider the scheme of operators\n\n\[ E\overset{{S}_{1}}{ \rightarrow }F\overset{{S}_{2}}{ \rightarrow }X \]\n\nwhere \( {S}_{1} \) is a positive operator and dominated by a DPcc oprator. If \( {S}_{2} \) is order weak...
Proof By [1, Theorem 5.58, p. 319], the operator \( {S}_{2} \) admits a factorization through a Banach lattice \( G \) with order continuous norm\n\n\[ F\overset{Q}{ \rightarrow }G\overset{S}{ \rightarrow }X \]\n\nsuch that \( Q \) is a lattice homomorphism and \( {S}_{2} = {SQ} \) . Obviously, the positive operator \(...
Yes
Lemma 3.1 Every DPcc operator \( T : E \rightarrow X \) from a Banach lattice to a Banach space is order weakly compact.
Proof Let \( \left( {x}_{n}\right) \) be an order bounded disjoint sequence of \( E \) . Then \( {x}_{n}\overset{\mathrm{w}}{ \rightarrow }0 \) holds in \( E \) . On the other hand, \( \left( {x}_{n}\right) \) is a DP set by [3, Theorem 2.5]. So \( \lim \begin{Vmatrix}{T{x}_{n}}\end{Vmatrix} \rightarrow 0 \) . The conc...
Yes
If \( X = \{ \left\lbrack {a, b}\right\rbrack : a, b \in \mathbb{R}, a \leq b\} \), then \( p(\left\lbrack {a, b}\right\rbrack ,\left\lbrack {c, d}\right\rbrack ) = \max \{ a, b\} - \min \{ c, d\} \) defines a partial metric \( p \) on \( X \) .
Each partial metric \( p \) on \( X \) generates a \( {T}_{0} \) topology \( {\tau }_{p} \) on \( X \) which has as a base the family of open \( p \) -balls \( \left\{ {{B}_{p}\left( {x,\varepsilon }\right) : x \in X,\varepsilon > 0}\right\} \), where \( {B}_{p}\left( {x,\varepsilon }\right) = \{ y \in X : p\left( {x, ...
No
Lemma 1.2 \( {}^{\left\lbrack {11}\right\rbrack } \) Let \( \left( {X, p}\right) \) be a partial metric space and let \( \left\{ {y}_{n}\right\} \) be a sequence in \( X \) such that \( \mathop{\lim }\limits_{{n \rightarrow \infty }}p\left( {{y}_{n},{y}_{n + 1}}\right) = 0 \) . If \( \left\{ {y}_{2n}\right\} \) is not ...
\[ p\left( {{y}_{{2m}\left( k\right) },{y}_{{2n}\left( k\right) }}\right) ,\;p\left( {{y}_{{2m}\left( k\right) },{y}_{{2n}\left( k\right) + 1}}\right) ,\;p\left( {{y}_{{2m}\left( k\right) - 1},{y}_{{2n}\left( k\right) }}\right) ,\;p\left( {{y}_{{2m}\left( k\right) - 1},{y}_{{2n}\left( k\right) + 1}}\right) . \]
Yes
Theorem 2.1 Let \( \\left( {X, p, \\preccurlyeq }\\right) \) be a complete ordered partial metric space such that \( X \) is regular. Let \( T : X \\rightarrow X \) be a self-mapping and \( {\\left\{ {f}_{k}\\right\} }_{k = 1}^{\\infty } \) be a sequence of mappings of \( X \) into itself. Suppose that for every \( i, ...
Proof Let \( {x}_{0} \) be an arbitrary point in \( X \). Since \( {f}_{1}X \\subseteq {TX} \), there exists an \( {x}_{1} \\in X \) such that \( T{x}_{1} = {f}_{1}{x}_{0} \). Since \( {f}_{2}X \\subseteq {TX} \), there exists an \( {x}_{2} \\in X \) such that \( T{x}_{2} = {f}_{2}{x}_{1} \). Continuing this process, w...
Yes
The Euler-Lagrange equation of the volume variational problem with respect to the \( F \) -relative metric is
\[ 0 = \left\lbrack {\frac{{n}^{2}}{8}\frac{{F}^{\prime }}{{\rho }^{2}} + \frac{n\left( {n + 2}\right) }{8}\frac{F}{{\rho }^{3}} - \frac{n\left( {n - 2}\right) \left( {n - 4}\right) }{8\left( {n + 2}\right) }\frac{{F}^{\prime 3}}{{F}^{2}} - \frac{n\left( {n - 2}\right) \left( {n + 6}\right) }{8\left( {n + 2}\right) }\f...
Yes
Lemma 1.7 Let\n\[ L = \\left( \\begin{matrix} A & B \\\\ {B}^{\\mathrm{T}} & D \\end{matrix}\\right) \]\n\nbe the Laplacian matrix of a connected graph. If \( D \) is nonsingular, then\n\n\[ X = \\left( \\begin{matrix} {H}^{\\# } & - {H}^{\\# }B{D}^{-1} \\\\ - {D}^{-1}{B}^{\\mathrm{T}}{H}^{\\# } & {D}^{-1} + {D}^{-1}{B...
Proof Since \( H = A - B{D}^{-1}{B}^{\\mathrm{T}} \) is symmetric, \( {H}^{\\# } \) exists and is symmetric. Since\n\n\[ L = \\left( \\begin{matrix} I & B{D}^{-1} \\\\ 0 & I \\end{matrix}\\right) \\left( \\begin{matrix} H & 0 \\\\ 0 & D \\end{matrix}\\right) \\left( \\begin{matrix} I & 0 \\\\ {D}^{-1}{B}^{\\mathrm{T}} ...
Yes
Theorem 2.1 Let \( {G}_{1} \) be an \( {r}_{1} \) -regular graph with \( {n}_{1} \) vertices and \( {m}_{1} \) edges, \( {G}_{2} \) and \( {G}_{3} \) be respectively two arbitrary graphs on \( {n}_{2},{n}_{3} \) vertices. Then \( G = {G}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right) \) has the resistance d...
Proof Let \( R \) be the incidence matrix of \( {G}_{1} \) . Then with a proper labeling of vertices, the Laplacian matrix of \( G = {G}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right) \) can be written as\n\n\[ L\left( G\right) = \left( \begin{matrix} \left( {{r}_{1} + {n}_{2}}\right) {I}_{{n}_{1}} & - R & ...
Yes
Theorem 3.1 Let \( {G}_{1} \) be an \( {r}_{1} \) -regular graph with \( {n}_{1} \) vertices and \( {m}_{1} \) edges, \( {G}_{2} \) and \( {G}_{3} \) be respectively two arbitrary graphs on \( {n}_{2},{n}_{3} \) vertices. Then the Kirchhoff index of \( G = \) \( {G}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\r...
Proof Let \( G = {G}_{1}^{S} \circ \left( {{G}_{2}^{V} \cup {G}_{3}^{E}}\right) \), and \( {L}_{G}^{\left( 1\right) } \) be the symmetric \( \{ 1\} \) -inverse of \( {L}_{G} \) given in (2.1). Then\n\n\[ \operatorname{tr}\left( {L}_{G}^{\left( 1\right) }\right) = 2\operatorname{tr}\left( {L}_{{G}_{1}}^{\# }\right) + \o...
Yes
Lemma 7 Every planar graph \( G \) can be decomposed into two forests \( {F}_{1},{F}_{2} \) and one subgraph \( H \) such that, for every vertex \( v \) in \( G,{d}_{H}\left( v\right) \leq {11} \), and\n\n(1) if \( {d}_{G}\left( v\right) > {11} \), then \( {d}_{{F}_{i}}\left( v\right) \leq \lceil \frac{{d}_{G}\left( v\...
Proof If \( \Delta \left( G\right) \leq 5 \), the result holds trivially. Now suppose that \( \Delta \left( G\right) \geq 6 \) . By Corollary \( 1, G \) has an edge-partition into two forests \( {F}_{1},{F}_{2} \) and a subgraph \( H \) with \( \Delta \left( {F}_{i}\right) \leq \lceil \frac{\Delta \left( G\right) }{2}\...
Yes
Lemma 3 Let \( k \geq 2 \) be an integer and \( N \) be a unitary \( k \) -perfect number. Then\n\n\[ \omega \left( N\right) > \max \left\{ {s : \mathop{\prod }\limits_{{i = 1}}^{s}\left( {1 + \frac{1}{{P}_{i}}}\right) < k}\right\} \]\n\nwhere \( {P}_{i} \) denotes the \( i \) -th prime.
Proof Let \( N = {p}_{1}^{{\alpha }_{1}}{p}_{2}^{{\alpha }_{2}}\cdots {p}_{t}^{{\alpha }_{t}} \) be the standard prime factorization of \( N \) . Since \( {p}_{i} \geq {P}_{i} \) for \( i = 1,2,\cdots, t \), we have\n\n\[ k = \frac{{\sigma }^{ * }\left( N\right) }{N} = \mathop{\prod }\limits_{{i = 1}}^{t}\frac{1 + {p}_...
Yes
Lemma 1.1 Let \( R \) be a finite chain ring with maximal ideal \( \langle \gamma \rangle \), index of nilpotency \( e \) even and \( \left| K\right| = \frac{\left| R\right| }{\left| \langle \gamma \rangle \right| } = {p}^{r} = q \) . Then nontrivial self-dual cyclic codes of length \( n \) over \( R \) exist if and on...
Proof of Theorem 0.1 Suppose that (i) is satisfied. Without loss of generality, let \( {\operatorname{ord}}_{{p}_{1}}\left( q\right) = {\widehat{c}}_{1} \) be odd. We need to prove that \( {q}^{i} ≢ - 1\left( {\;\operatorname{mod}\;n}\right) \) for all positive integers \( i \) . Suppose otherwise that there exists som...
Yes
Theorem 1.1 Let \( {T}_{\theta } \) be a \( B \) -algebra and \( \operatorname{Hom}\left( {{T}_{\theta },{T}_{\theta }}\right) \) be the vector space spanned by \( B \) -algebra homomorphisms of \( {T}_{\theta } \) . Then \( \operatorname{Hom}\left( {{T}_{\theta },{T}_{\theta }}\right) \) is a subalgebra of the general...
Proof The result follows from Definition 1.1, directly.
No
Theorem 1.2 Let \( L \) be a 3-Lie algebra and \( T\left( L\right) = L\dot{ + }\operatorname{Der}\left( L\right) \) (the direct sum of vector spaces). Then \( \left( {T{\left( L\right) }_{\theta },\left\lbrack {\cdot , \cdot }\right\rbrack }\right) \) is a \( B \) -algebra, where the multiplication \( \left\lbrack {\cd...
Proof From Eq. (1.4), \( \left( {T\left( L\right) ,\left\lbrack {\cdot , \cdot }\right\rbrack }\right) \) is an anticommutative algebra. And for all \( x, y \in \) \( L,{D}_{1},{D}_{2} \in \operatorname{Der}\left( L\right) \) \[ \left\lbrack {\theta \left( {x + {D}_{1}}\right) ,\theta \left( {y + {D}_{2}}\right) }\righ...
Yes
Theorem 1.3 Let \( {T}_{\theta } \) be a \( B \) -algebra. Then\n\n(1) \( \operatorname{Der}\left( {T}_{0}\right) = \left\{ {D \in \operatorname{Der}\left( T\right) \mid D\left( {T}_{0}\right) \subset {T}_{0}}\right\} \) is a subalgebra of \( \operatorname{Der}\left( T\right) \), \n\n(2) \( \iota \left( {T}_{0}\right) ...
Proof The result follows from the direct computation according to Definition 1.1.
No
Theorem 2.1 Let \( \left( {T,\left\lbrack {\cdot , \cdot }\right\rbrack ,\theta }\right) \) be a \( B \) -algebra. Then \( \left( {{T}_{0},\left\lbrack {\cdot , \cdot }\right\rbrack }\right) \) is a Lie algebra, and \( {T}_{1} \) is a 3-Lie algebra in the multiplication\n\n\[ \left\lbrack {x, y, z}\right\rbrack = \left...
Proof By Definition 1.1, \( \left( {{T}_{0},\left\lbrack {\cdot , \cdot }\right\rbrack }\right) \) is a Lie algebra, and the ternary multiplication \( \left\lbrack {x, y, z}\right\rbrack \) defined by Eq. (2.1) is skew-symmetric. For any \( x, y, z, u, v \in {T}_{1} \), by Definition 1.1,\n\n\[ \left\lbrack {\left\lbra...
Yes
Theorem 2.4 Let \( L \) be a 3-Lie algebra. Then \( \left( {\mathrm{{SB}}{\left( L\right) }_{\theta },\pi }\right) \) is an enveloping \( B \) -algebra of \( L \) , where \( \pi : L \rightarrow \mathrm{{SB}}\left( L\right) ,\pi \left( x\right) = - x,\forall x \in L.\mathrm{{SB}}{\left( L\right) }_{\theta } \) is called...
Proof By the above discussion, \( \pi : L \rightarrow \mathrm{{SB}}\left( L\right) ,\pi \left( x\right) = - x,\forall x \in L \) satisfies \( \pi \left( \left\lbrack {x, y, z}\right\rbrack \right) = \) \( \left\lbrack {\left\lbrack {\pi \left( x\right) ,\pi \left( y\right) }\right\rbrack ,\pi \left( z\right) }\right\rb...
Yes
Theorem 2.6 Let \( L \) be a 3-Lie algebra over a field \( F \) with \( \operatorname{ch}F \neq 2 \) . If \( I \) is an ideal of the \( B \) -algebra \( \operatorname{SB}{\left( L\right) }_{\theta } \), then\n\n(1) \( {I}_{L} \) and \( {I}_{\mathrm{{Ad}}} \) are an ideal of the 3-Lie algebra \( L \) and the Lie algebra...
Proof If \( x \in {I}_{L} \), then there exists \( D \in \operatorname{ad}\left( L\right) \) such that \( x + D \in I \) . Thus \( \forall y, z \in L \) ,\n\n\[ \left\lbrack {x + D,\operatorname{ad}\left( {y, z}\right) }\right\rbrack = - \left\lbrack {x, y, z}\right\rbrack - \operatorname{ad}\left( {D\left( y\right), z...
Yes
Lemma 1.3 \( {}^{\left\lbrack {10}\right\rbrack } \) Let \( k \in \mathbb{Z}, h \in {\Lambda }_{1}^{\eta }\left( {\mathbb{R}}^{ + }\right), m \in \mathbb{N} \) and \( R \) be a real-valued polynomial on \( {\mathbb{R}}^{n} \) with \( \deg \left( R\right) \leq m - 1 \) . Suppose that \( P\left( y\right) = \mathop{\sum }...
\[ \left| {{\int }_{{\rho }^{k} \leq \left| y\right| < {\rho }^{k + 1}}{\mathrm{e}}^{-\mathrm{i}P\left( y\right) }\frac{\Omega \left( y\right) h\left( \left| y\right| \right) }{{\left| y\right| }^{n}}\mathrm{\;d}y}\right| \leq C\left( {\log \rho }\right) \parallel h{\parallel }_{{\Lambda }_{1}^{\eta }\left( {\mathbb{R}...
Yes
Lemma 1.5 Let \( 1 < q \leq 2,\Omega, h \) be as in Lemma 1.4. Let \( {N}_{0},{M}_{0} \in \mathbb{N},{R}_{1} \) and \( {R}_{2} \) be real-valued polynomials on \( {\mathbb{R}}^{n} \) and \( {\mathbb{R}}^{m} \), respectively with \( \deg \left( {R}_{1}\right) \leq {N}_{0} - 1 \) and \( \deg \left( {R}_{2}\right) \leq {M...
\[ \left| {{\int }_{{I}_{k, j}}{\mathrm{e}}^{-\mathrm{i}\left( {P\left( x\right) + Q\left( y\right) }\right) }\frac{\Omega \left( {x, y}\right) h\left( {\left| x\right| ,\left| y\right| }\right) }{{\left| x\right| }^{n}{\left| y\right| }^{m}}\mathrm{\;d}x\mathrm{\;d}y}\right| \] \[ \leq C{\left( \log \rho \right) }^{2}...
Yes
Lemma 2.2 Let \( \mathcal{P} = \left( {{P}_{1},{P}_{2},\cdots ,{P}_{n}}\right) : {\mathbb{R}}^{n} \rightarrow {\mathbb{R}}^{n} \) and \( \mathcal{Q} = \left( {{Q}_{1},{Q}_{2},\cdots ,{Q}_{m}}\right) : {\mathbb{R}}^{m} \rightarrow {\mathbb{R}}^{m} \) be polynomial mappings. Let \( q \in (1,2\rbrack ,\Omega \in {L}^{q}\l...
\[ \parallel {\lambda }_{\mathcal{P},\mathcal{Q}}^{ * }f{\parallel }_{{L}^{p}} \leq C{\left( \log \rho \right) }^{2}\parallel h{\parallel }_{{\widetilde{\Lambda }}_{\gamma }^{\eta }}\parallel \Omega {\parallel }_{{L}^{q}\left( {{\mathbb{S}}^{n - 1} \times {\mathbb{S}}^{m - 1}}\right) }\parallel f{\parallel }_{{L}^{p}}....
Yes
Lemma 2.3 Let \( \Phi : {B}_{n}\left( {0,1}\right) \rightarrow {\mathbb{R}}^{n} \) and \( \Psi : {B}_{m}\left( {0,1}\right) \rightarrow {\mathbb{R}}^{m} \) be smooth mappings. Let \( \mathcal{P} = \left( {{P}_{1},{P}_{2},\cdots ,{P}_{n}}\right) : {\mathbb{R}}^{n} \rightarrow {\mathbb{R}}^{n} \) and \( \mathcal{Q} = \le...
Proof We shall only prove (2.3). The proof of (2.4) is similar. By Hölder’s inequality, it is easy to check that \[ {\lambda }_{\mathcal{P},\Psi }^{ * }f\left( {x, y}\right) \leq {\left( \mathop{\sup }\limits_{{k \leq {k}_{0}}}{\int }_{{\rho }^{k}}^{{\rho }^{k + 1}}\mathop{\sup }\limits_{{j \leq {j}_{0}}}{\int }_{{\rho...
Yes
Theorem 1.1 Let \( \varphi \) be an anisotropic growth function as in Definition 1.3. Then\n\n\[ \n{T}_{A}^{\varphi }\left( {{\mathbb{R}}^{n} \times \mathbb{Z}}\right) = {T}_{A}^{\varphi ,\infty }\left( {{\mathbb{R}}^{n} \times \mathbb{Z}}\right)\n\]\n\nwith equivalent (quasi-) norms.
To show Theorem 1.1, we need some technical lemmas. For \( \left( {\varphi ,\infty }\right) \) -atoms, we have the following lemma which is an anisotropic variant of [14, Lemma 3.1]. It is worth mentioning that, we simplify the proof of \( \left\lbrack {{14}\text{, Lemma 3.1}}\right\rbrack \) in our anisotropic setting...
No
Lemma 1.1 Let \( \varphi \) be an anisotropic growth function as in Definition 1.3. Then, for any \( \left( {\varphi ,\infty }\right) \) -atom \( a \), it holds that \( a \in {T}_{A}^{\varphi }\left( {{\mathbb{R}}^{n} \times \mathbb{Z}}\right) \) . Moreover, there exists a positive constant \( C \) such that, for any \...
Proof Let \( a \) be a \( \left( {\varphi ,\infty }\right) \) -atom. Assume first that (1.8) holds for a moment. By (1.8) with \( \lambda = 1 \) and \( \varphi \left( {B,\frac{1}{\parallel {\chi }_{B}{\parallel }_{{L}^{\varphi }\left( {\mathbb{R}}^{n}\right) }}}\right) = 1 \), we see that there exists a positive consta...
Yes
Lemma 1.3 There exist positive constants \( \gamma \in \left( {0,1}\right) \) and \( {C}_{\left( \gamma \right) } \), depending on \( \gamma \), such that, for any closed subset \( F \) of \( {\mathbb{R}}^{n} \) whose complement has finite measure, and any nonnegative measurable function \( H \) on \( {\mathbb{R}}^{n} ...
Proof We claim that there exist positive constants \( \gamma \in \left( {0,1}\right) \) and \( {C}_{\left( \gamma \right) } \) such that, for any closed subset \( F \) of \( {\mathbb{R}}^{n} \) and \( \left( {y, k}\right) \in \Gamma \left( {F}_{\gamma }^{ * }\right) \),\n\n\[ {\int }_{F}{\chi }_{y + {B}_{k}}\left( x\ri...
Yes
Lemma 2.4 Let \( \varphi \) be an anisotropic growth function as in Definition 1.3 satisfying \( q\left( \varphi \right) < \) \( i\left( \varphi \right) \left\lbrack {1 + {\log }_{b}\left( {\lambda }_{ - }\right) }\right\rbrack \), where \( q\left( \varphi \right) \) and \( i\left( \varphi \right) \) are, respectively,...
Proof The proof of Lemma 2.4 is similar to that of [18, Theorem 3.2] with a slight modification, the details being omitted. There is just one remark on the condition of the anisotropic growth function \( \varphi \) satisfying \( q\left( \varphi \right) < i\left( \varphi \right) \left\lbrack {1 + {\log }_{b}\left( {\lam...
No
Theorem 3.1 (Weak duality) Let \( x \in F,\left( {y,{u}^{ * },{v}^{ * }}\right) \in G \), and \( {u}^{ * } \in {C}^{ * } \smallsetminus \left\{ {0}_{{Y}^{ * }}\right\} \) (or \( {u}^{ * } \in \operatorname{int}{C}^{ * } \) ). Furthermore, suppose that one of the following conditions holds with respect to \( {b}_{0},{b}...
Proof Assume to the contrary that there exist \( \breve{x} \in F,\left( {y,{u}^{ * },{v}^{ * }}\right) \in G \) such that\n\n\[ f\left( \breve{x}\right) { < }_{C}f\left( y\right) \;\left( {\text{ or }f\left( \breve{x}\right) { \leq }_{C}f\left( y\right) }\right) .\n\]\n\nBy \( {u}^{ * } \in {C}^{ * } \smallsetminus \le...
Yes
Theorem 3.2 (Strong duality) Let \( \bar{x} \) be a weakly efficient solution for the problem (P) at which the Slater regularity condition is satisfied, \( f, g \) be directionally differentiable \( \alpha \) -preinvex on \( \alpha \) -invex set \( K \subset X \) . Moreover, suppose that one of the following conditions...
Proof Since \( \bar{x} \) satisfies all the conditions of Lemma 1.2, there exist \( {\bar{u}}^{ * } \in {C}^{ * },{\bar{u}}^{ * } \neq \) \( {0}_{{Y}^{ * }},{\bar{v}}^{ * } \in {D}^{ * } \) such that \( \left\langle {{\bar{v}}^{ * }, g\left( \bar{x}\right) }\right\rangle = 0 \) and \( \left( {\bar{x},{\bar{u}}^{ * },{\...
Yes
Theorem 3.3 (Converse duality) Let \( \left( {\bar{y},{\bar{u}}^{ * },{\bar{v}}^{ * }}\right) \) be a weakly efficient (or an efficient) solution for the problem (D). Assume that \( {\bar{u}}^{ * } \in {C}^{ * } \smallsetminus \left\{ {0}_{{Y}^{ * }}\right\} \) (or \( {\bar{u}}^{ * } \in \operatorname{int}{C}^{ * } \) ...
Proof Assume contrary to the result that \( \bar{y} \) is not a weakly efficient (or an efficient) solution for the problem (P), then there exists \( \breve{y} \in F \) such that\n\n\[ f\left( \breve{y}\right) { < }_{C}f\left( \bar{y}\right) \;\left( {\text{ or }f\left( \breve{y}\right) { \leq }_{C}f\left( \bar{y}\righ...
Yes
Proposition 2.1 (i) If \( x \in K \) is a solution of (WVVI), then it is a solution of (WVICP).
Proof (i) Let \( x \in K \) be a solution of (WVVI). Then\n\n\[ \langle T\left( x\right), y - g\left( x\right) \rangle \notin - \operatorname{int}C\left( x\right) ,\;\forall y \in K. \]\n\n(2.1)\n\nSetting \( y = {\theta }_{X} \) (the origin of \( X \) ) in (2.1), we have\n\n\[ \langle T\left( x\right), g\left( x\right...
Yes
Proposition 2.2 (SVVI) and (SVICP) have the same solution set.
Proof (I) Let \( x \in K \) be a solution of (SVVI). Then\n\n\[ \langle T\left( x\right), y - g\left( x\right) \rangle \in C\left( x\right) ,\;\forall y \in K. \]\n\n(2.5)\n\nSetting \( y = {\theta }_{X} \) in (2.5), we have\n\n\[ \langle T\left( x\right), g\left( x\right) \rangle \in - C\left( x\right) \]\n\n(2.6)\n\n...
Yes
Theorem 3.1 Let \( D \) be a nonempty, compact convex subset of Banach space \( X \) . Assume that\n\n(i) mappings \( T : D \rightarrow L\left( {X, Y}\right) \) and \( g : D \rightarrow D \) are continuous;\n\n(ii) \( \forall x \in D,\langle T\left( x\right), x\rangle - \langle T\left( x\right), g\left( x\right) \rangl...
Proof By contradiction, suppose that the (WVVI) is not solvable. Then \( \forall x \in D \), there is some \( y \in D \) such that\n\n\[ \langle T\left( x\right), y - g\left( x\right) \rangle \in - \operatorname{int}C\left( x\right) . \]\n\nDefine set-valued mapping \( S : D \rightarrow {2}^{D} \) as follows. For each ...
Yes
Corollary 4.1 Let \( X \) and \( K \) be the same as in Theorem 4.1. Assume that the conditions (i)-(iii) in Theorem 4.1 and the following condition (iv)' hold:\n\n(iv)’ there exists a real number \( r > 0 \) such that, \( \forall x \in K,\parallel x\parallel \geq r \), one has\n\n\[ \langle T\left( x\right), g\left( x...
Proof In Theorem 4.1, choose \( {v}_{x} = {\theta }_{X} \) . Then Theorem 4.1 yields the conclusion. This completes the proof.
No
Corollary 4.2 Let \( X \) and \( K \) be the same as in Theorem 4.1. Assume that the conditions (i)-(iii) in Theorem 4.1 and the following condition (iv)' hold:\n\n(iv)' there exist a real number \( {r}_{0} > 0 \) and some \( {v}_{0} \in K \) such that, \( \forall x \in K,\parallel x\parallel \geq {r}_{0} \), one has\n...
Proof In Theorem 4.1, let \( r = 1 + \max \left\{ {{r}_{0},\begin{Vmatrix}{v}_{0}\end{Vmatrix}}\right\} \), and for each \( x \in K,\parallel x\parallel \geq r \), choose \( {v}_{x} = {v}_{0} \). Then Theorem 4.1 yields the conclusion. This completes the proof.
Yes
Theorem 4.2 Let \( X \) be a reflexive Banach space, and \( K{\left( {K}_{n}\right) }_{n \in \mathbb{N}} \) be a Galerkin cone of \( X \) . Assume that the following conditions hold:\n\n(i) mappings \( T : K \rightarrow L\left( {X, Y}\right) \) and \( g : K \rightarrow K \) are strongly continuous;\n\n(ii) \( \forall x...
Proof For each \( n \geq {n}_{0} \), by Theorem 4.1, the (WVVI) has a solution \( {x}_{n} \in {K}_{n} \) and \( \begin{Vmatrix}{x}_{n}\end{Vmatrix} < r \) . Since \( X \) is reflexive and the sequence \( \left\{ {x}_{n}\right\} \subseteq K \) is bounded, it has a weakly convergent subsequence (for simplification, we st...
Yes
Theorem 5.1 Let \( X \) be a Banach space, \( K \subseteq X \) a locally compact convex cone. Assume that\n\n(i) \( C : K \rightarrow {2}^{Y} \) is closed;\n\n(ii) mappings \( T : K \rightarrow L\left( {X, Y}\right) \) and \( g : K \rightarrow K \) are continuous;\n\n(iii) there is a mapping \( h : K \times K \rightarr...
Proof By Proposition 2.2, we only need to show that the (SVVI) is solvable in \( K \) .\n\nIn fact, \( \forall n \in \mathbb{N} \), let \( {D}_{n} = \{ x \in K : \parallel x\parallel \leq n\} \) . It follows from the local compactness of \( K \) that \( {D}_{n} \) is compact and convex. By Theorem 3.2, there is an \( {...
Yes
Theorem 5.2 Let \( X \) be a reflexive Banach space, and \( K{\left( {K}_{n}\right) }_{n \in \mathbb{N}} \) be a Galerkin cone of \( X \) . Assume that the following conditions hold:\n\n(i) \( C : K \rightarrow {2}^{Y} \) is closed;\n\n(ii) mappings \( T : K \rightarrow L\left( {X, Y}\right) \) and \( g : K \rightarrow...
Proof For \( n \geq {n}_{0} \), by Theorem 5.1, the (SVVI) has a solution \( {x}_{n} \in {K}_{n} \), and \( \begin{Vmatrix}{x}_{n}\end{Vmatrix} < \) \( r \) . Since \( X \) is reflexive and the sequence \( \left\{ {x}_{n}\right\} \subseteq K \) is bounded, it has a weakly convergent subsequence (for simplification, we ...
Yes
Theorem 0.5 Let \( G \) be a graph with \( \Delta \left( G\right) = 3 \) and \( \mathrm{{mad}}\left( G\right) < \frac{44}{15}. \) Then \( {\mathrm{{ch}}}_{\sum }^{\prime \prime }\left( G\right) \leq 6.
Our proof proceeds by contradiction. Let \( G \) be a counterexample to Theorem 0.5 such that \( \left| {V\left( G\right) }\right| + \left| {E\left( G\right) }\right| \) is as small as possible. Clearly, \( G \) is connected. Let \( {\left( {L}_{x}\right) }_{x \in V \cup E} \) be any given set of lists of real numbers,...
Yes
Theorem 1.1 Let \( G \) be a cubic graph of order \( n \) . Then \( \nabla \left( G\right) = \left\lceil \frac{n + 2}{4}\right\rceil \) if and only if \( G \) is upper-embeddable.
In fact, Theorem 1.1 not only answers the question proposed by Bau and Beineke, but also generalizes one result of Xuong in [11] where it is proved that if there is a set \( A \) with cardinality \( \left\lfloor \frac{{3n} - 2}{4}\right\rfloor \) in a cubic graph \( G \) such that \( G\left\lbrack A\right\rbrack \) is ...
No
Lemma 2.1 Let \( G \) be a cubic graph of order \( n \) . Then \( \nabla \left( G\right) \geq \left\lceil \frac{n + 2}{4}\right\rceil \) .
Proof Suppose that \( S \) is a \( \nabla \) -set of \( G \) and there are \( c \) components in \( G - S \) . Then \( \left| {E\left( {G - S}\right) }\right| = n - \left| S\right| - c \) . On the other hand we know \( \left| {{N}_{E}\left( S\right) }\right| \leq 3\left| S\right| \) and equality holds if and only if \(...
Yes
Lemma 3.1 Let \( G \) be a cubic graph. Then\n\n\[ \nabla \left( G\right) \leq {\gamma }_{M}\left( G\right) + \xi \left( G\right) \]
Proof Let \( {T}_{X} \) be a Xuong tree of \( G \) . By Theorem 1.5,\n\n\[ E\left( G\right) - E\left( {T}_{X}\right) = \left\{ {{e}_{1},{e}_{2}}\right\} \cup \left\{ {{e}_{3},{e}_{4}}\right\} \cup \cdots \cup \left\{ {{e}_{{2m} - 1},{e}_{2m}}\right\} \cup \left\{ {{f}_{1},{f}_{2},\cdots ,{f}_{s}}\right\} \]\n\nhere \( ...
Yes
Theorem 1 Let\n\n\\[ \n{S}_{k}\left( x\right) = \mathop{\sum }\limits_{\substack{{1 \leq {n}_{1},{n}_{2} \leq {x}^{\frac{1}{2}}} \\ {1 \leq {n}_{3} \leq {x}^{\frac{1}{k}}} }}d\left( {{n}_{1}^{2} + {n}_{2}^{2} + {n}_{3}^{k}}\right) ,\\;3 \leq k \in \mathbb{N}. \n\\] \n\nThen we have\n\n\\[ \n{S}_{k}\left( x\right) = {C}...
We establish Theorem 1 by means of the circle method. In order to estimate the sum of divisor effectively, we employ the results obtained by Guo and Zhai (see [2, Lemma 7.1]).\n\n## 1 Preliminaries\n\nThroughout this paper, \\( x \\) is a large positive integer. For any \\( \\alpha \\in \\mathbb{R} \\), put\n\n\\[ \n{f...
Yes
Lemma 1.1 For any \( a, q \in \mathbb{Z} \) with \( \left( {q, a}\right) = 1 \) and \( q > 0 \), let\n\n\[ \n{S}_{k}\left( {q, a}\right) = \mathop{\sum }\limits_{{r = 1}}^{q}e\left( {\frac{a}{q}{r}^{k}}\right) .\n\]\n\nThen we have\n\n\[ \n{S}_{k}\left( {q, a}\right) \ll {q}^{\frac{k - 1}{k}}.\n\]
Proof See \( \left\lbrack {4\text{, Theorem 4.2}}\right\rbrack \) .
No
Lemma 1.2 For \( k \geq 1 \), we have\n\ni)\n\n\[ \n{\int }_{0}^{1}e\left( {\beta {\mu }^{k}}\right) \mathrm{d}\mu \ll \frac{1}{{\left( 1 + \left| \beta \right| \right) }^{\frac{1}{k}}}\n\]\n\nii)\n\n\[ \n{\int }_{0}^{3}e\left( {\beta \mu }\right) \log \mu \mathrm{d}\mu \ll \frac{\log \left( {2 + \left| \beta \right| }...
Proof For i), it follows from integration by parts together with trivial bounds. For ii), when \( \left| \beta \right| > 1 \), we have\n\n\[ \n{\int }_{0}^{3}e\left( {\beta \mu }\right) \log \mu \mathrm{d}\mu = \left( {{\int }_{0}^{\frac{1}{\left| \beta \right| }} + {\int }_{\frac{1}{\left| \beta \right| }}^{3}}\right)...
Yes
Lemma 1.3 Suppose that \( \left( {a, q}\right) = 1 \) and \( \alpha = \frac{a}{q} + \beta \) . Then\n\n\[ \n{f}_{k}\left( \alpha \right) = {V}_{k}\left( {\alpha, q, a}\right) + O\left( {{q}^{\frac{1}{2} + \varepsilon }{\left( 1 + x\left| \beta \right| \right) }^{\frac{1}{2}}}\right) .\n\]\n\nIf further \( \left| \beta ...
Proof See [4, Theorem 4.1].
No
Lemma 1.4 Suppose that \( \alpha = \frac{a}{q} + \beta \in \mathfrak{M} \) and \( {Q\tau } \leq x,\tau > {x}^{\frac{1}{2} + \varepsilon } \). Then\n\n\[ f\left( {-\alpha }\right) = \frac{x\log x}{q}{\int }_{0}^{3}e\left( {-{\mu x\beta }}\right) \mathrm{d}\mu + \frac{x}{q}{\int }_{0}^{3}e\left( {-{\mu x\beta }}\right) \...
Proof See [2, Lemma 7.1].
No
Lemma 1.5 Suppose \( M > 0, N > 0,{u}_{m} > 0,{v}_{n} > 0,{A}_{m} > 0,{B}_{n} > 0(1 \leq m \leq \) \( M,1 \leq n \leq N \) ), and let \( {Q}_{1} \) and \( {Q}_{2} \) be given non-negative numbers, \( {Q}_{1} \leq {Q}_{2} \) . Then there is a \( q \) such that \( {Q}_{1} \leq q \leq {Q}_{2} \) and\n\n\[ \mathop{\sum }\l...
Proof This is \( \left\lbrack {3\text{, Lemma 3}}\right\rbrack \) .
Yes
Lemma 1.6 Let \( j \) be an integer with \( j \geq 2 \) . Suppose that there exist integers \( a, q \) with \( q \geq 1,\left( {a, q}\right) = 1 \) such that \( \left| {\alpha - \frac{a}{q}}\right| \leq {q}^{-2} \) and \( q \leq x \) . Then one has \[ {f}_{j}\left( \alpha \right) \ll {x}^{\frac{1}{j} + \varepsilon }{\l...
Proof See [5, Theorem 1.5]. This conclusion is superior to Weyl’s inequality for \( j \geq 8 \) .
No
Lemma 1.1 If \( u \) is a solution of \( \left( {0.3}\right) –\left( {0.4}\right) \) with \( {2n} \) - \( 2 \) interior zeros with \( {u}^{\prime }\left( 0\right) > 0,\;u\left( 0\right) > \) \( 0,{u}^{\prime }\left( 1\right) < 0 \) and \( u\left( 1\right) > 0 \), then for \( \alpha \geq 0,\beta \geq 0 \) ,\n\n\[{\lambd...
Proof Let \( u \) be a solution of (0.3)-(0.4) with \( {2n} - 2 \) interior zeros with \( {u}^{\prime }\left( 0\right) = m > 0 \) , \( u\left( 0\right) > 0,{u}^{\prime }\left( 1\right) = - r < 0 \) and \( u\left( 1\right) > 0 \) . Denote \( {x}_{0} \) as the first critical point, \( {x}_{1} \) and \( {x}_{2} \) as the ...
Yes
Lemma 1.3 Given \( n \in \mathbb{N},\alpha ,\beta \in \left( {0,\infty }\right) \) and \( \rho \in \left( {\theta ,\infty }\right) \). (a) If \( u\left( x\right) \) is a sign-changing solution with \( {2n} - 1 \) interior zeros with \( u\left( 0\right) < 0,{u}^{\prime }\left( 0\right) < 0,{u}^{\prime }\left( 1\right) <...
\[ {\lambda }^{\frac{1}{p}} = {G}_{{2n} - 1}\left( {\alpha ,\beta ,\rho }\right) = {\left( \frac{p - 1}{p}\right) }^{\frac{1}{p}}\left\{ {{2n}{\int }_{0}^{\rho }\frac{\mathrm{d}u}{{\left( F\left( \rho \right) - F\left( u\right) \right) }^{\frac{1}{p}}} + {2n}{\int }_{q}^{0}\frac{\mathrm{d}u}{{\left( F\left( q\right) - ...
Yes
Theorem 2.1 Let\n\n\\[ \n{\\lambda }_{n} = \\left( \\frac{p - 1}{p}\\right) {\\left\\{ 2n{\\int }_{0}^{\\theta }\\frac{\\mathrm{d}u}{{\\left( -F\\left( u\\right) \\right) }^{\\frac{1}{p}}} - {\\int }_{0}^{\\alpha {m}^{ * }}\\frac{\\mathrm{d}u}{{\\left( -F\\left( u\\right) \\right) }^{\\frac{1}{p}}} - {\\int }_{0}^{\\be...
Proof According to the quadrature technique, a solution with \\( {2n} - 2 \\) interior zeros exists if for \\( \\lambda > 0 \\) there exists \\( \\rho \\in \\left( {\\theta ,\\infty }\\right) \\) such that \\( {\\lambda }^{\\frac{1}{p}} = {G}_{{2n} - 2}\\left( {\\alpha ,\\beta ,\\rho }\\right) \\) . To prove this we wi...
Yes
Theorem 2.2 Let\n\n\[ \n{\lambda }_{n} = \left( \frac{p - 1}{p}\right) {\left\{ 2n{\int }_{0}^{\theta }\frac{\mathrm{d}u}{{\left( -F\left( u\right) \right) }^{\frac{1}{p}}} - {\int }_{0}^{\beta {r}^{ * }}\frac{\mathrm{d}u}{{\left( -F\left( u\right) \right) }^{\frac{1}{p}}}\right\} }^{p};\;n \in \mathbb{N}. \]\n\nThen f...
Proof It follows by analyzing \( {G}_{{2n} - 1}\left( {\alpha ,\beta ,\rho }\right) \) defined in (1.21) instead of \( {G}_{{2n} - 2}\left( {\alpha ,\beta ,\rho }\right) \) in the proof of Theorem 2.1.
Yes
Theorem 2.3 Let\n\n\\[ \n{\\lambda }_{n} = \\left( \\frac{p - 1}{p}\\right) {\\left\\{ 2n{\\int }_{0}^{\\theta }\\frac{\\mathrm{d}u}{{\\left( -F\\left( u\\right) \\right) }^{\\frac{1}{p}}}\\right\\} }^{p},\\;n \\in \\mathbb{N}. \n\\]\n\nThen for each \\( \\lambda \\in \\left( {0,{\\lambda }_{n}}\\right) \\) there exist...
Proof It follows by analyzing \\( {G}_{2n}\\left( {\\alpha ,\\beta ,\\rho }\\right) \\) defined in (1.25) instead of \\( {G}_{{2n} - 2}\\left( {\\alpha ,\\beta ,\\rho }\\right) \\) in the proof of Theorem 2.1.
Yes
Theorem 2.4 Let\n\n\[ \n{\lambda }_{n} = \left( \frac{p - 1}{p}\right) {\left\{ 2n{\int }_{0}^{\theta }\frac{\mathrm{d}u}{{\left( -F\left( u\right) \right) }^{\frac{1}{p}}} - {\int }_{0}^{\alpha {m}^{ * }}\frac{\mathrm{d}u}{{\left( -F\left( u\right) \right) }^{\frac{1}{p}}}\right\} }^{p},\;n \in \mathbb{N}. \]\n\nThen ...
Proof It follows by analyzing \( {G}_{{2n} - 1}^{1}\left( {\alpha ,\beta ,\rho }\right) \) defined in (1.29) instead of \( {G}_{{2n} - 2}\left( {\alpha ,\beta ,\rho }\right) \) in the proof of Theorem 2.1.
Yes