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002f7b238666396489e855316fa943dc12a864f0 | suppose firstly that γ and δ are two | suppose firstly that γ and δ are two geodesic rays with busemann functions differing by a constant. shifting the argument of one of the geodesics by a constant, it may be assumed that b = b = b, say. let c be the closed convex set on which b (x) ≤ − r. then b (γ(t)) = b (γ(t)) = − t and similarly b (δ(t)) = − t. then f... | wikipedia |
6b4b272adaee10d09e95485aeb7924e0519bbfa2 | hence h (y) = 0. similarly h (x) | hence h (y) = 0. similarly h (x) = 0. hence h (y) = 0 on the level surface of h containing x. now for t ≥ 0 and z in x, let α (z) = γ (t) the geodesic ray starting at z. then α = α ∘ α and h ∘ α = h − t. moreover, by boundedness, d (α (u),α (v)) ≤ d (u, v). the flow α can be used to transport this result to all the lev... | wikipedia |
ab716735c16fd1a335868f2b3bf306b6fea0d64d | fix x in x. let γ (s) be | fix x in x. let γ (s) be the geodesic ray starting at x. let g (z) = h (z), the busemann function for γ with base point x. in particular g (x) = 0. it suffices to show that g = h – h (y)1. now take y with h (x) = h (y) and let δ (t) be the geodesic ray starting at y corresponding to h. then | wikipedia |
da079fce593aa3b97a915034fefa807e16bae063 | let c be the closed convex set of | let c be the closed convex set of points z with h (z) ≤ − r. since x is a hadamard space for every point y in x there is a unique closest point p (y) to y in c. it depends continuously on y and if y lies outside c, then p (y) lies on the hypersurface h (z) = − r —the boundary ∂ c of c —and p (y) satisfies the inequalit... | wikipedia |
f0f0bc4fe1e7bae7b7c14695ea86f64f533123e5 | to prove the first assertion, it is enough | to prove the first assertion, it is enough to check this for t sufficiently large. in that case γ(t) and δ (t − h (y)) are the projections of x and y onto the closed convex set h ≤ − t. therefore, d (γ (t), δ (t − h (y))) ≤ d (x, y). hence d (γ (t), δ (t)) ≤ d (γ (t), δ (t − h (y))) + d (δ (t − h (y)), δ (t)) ≤ d (x, y... | wikipedia |
58187a5e1376fd8444d84b0fded7c2fdac0ebc3d | the third condition implies that v is the | the third condition implies that v is the closest point to y in the closed convex set c of points u {\displaystyle u} such that h (u) ≤ h (y) – r. let δ (t) for 0 ≤ t ≤ r be the geodesic joining y to v. then k (t) = h (δ (t)) - h (y) is a convex lipschitz function on with lipschitz constant 1 satisfying k (t) ≤ – t and... | wikipedia |
7f6a45094cea5b9d74ce663c1c6f91123e625b24 | comment. note that, since any closed convex subset | comment. note that, since any closed convex subset of a hadamard subset of a hadamard space is also a hadamard space, any closed ball in a hadamard space is a hadamard space. in particular it need not be the case that every geodesic segment is contained in a geodesic defined on the whole of r or even a semi-infinite in... | wikipedia |
3c2e0e86a062234b5eb4b4d4c826a5b7d9b717f1 | uniform limits. the above argument proves more generally | uniform limits. the above argument proves more generally that if d (x, x) tends to infinity and the functions h (x) = d (x, x) – d (x, x) tend uniformly on bounded sets to h (x), then h is convex, lipschitz with lipschitz constant 1 and, given y in x and r > 0, there is a unique point v with d (y, v) = r such that h (v... | wikipedia |
7a8b2eb701abf485c236cf749621a367ab794c3e | so that u is a cauchy sequence. if | so that u is a cauchy sequence. if u is its limit, then d (y, u) = r and h (u) = h (y) − r. by uniqueness it follows that u = v and hence d (y, v) = r, as required. | wikipedia |
a8b9faf3850e928a1ec5db7a24261e5f88bcced3 | let v be the closest point to y | let v be the closest point to y in c. then h (v) = h (y) − r and so h is minimised by v in b (y, r) where r = d (y, v) and v is the unique point where h is minimised. by the lipschitz condition r = | h (y) − h (v)| ≤ r. to prove the assertion, it suffices to show that r = r, i.e. d (y, v) = r. on the other hand, h is t... | wikipedia |
eac7c0b434f063fa383036a4dfb9ffbcc86cb01a | this condition persists for busemann functions. the statement | this condition persists for busemann functions. the statement and proof of the property for busemann functions relies on a fundamental theorem on closed convex subsets of a hadamard space, which generalises orthogonal projection in a hilbert space: if c is a closed convex set in a hadamard space x, then every point x i... | wikipedia |
3a7562af550b24fd2d6861dc8d78eb9c07a6c7d2 | next suppose that x, y are points in | next suppose that x, y are points in a hadamard space, and let δ (s) be the geodesic through x with δ (0) = y and δ (t) = x, where t = d (x, y). this geodesic cuts the boundary of the closed ball b (y, r) at the point δ (r). thus if d (x, y) > r, there is a point v with d (y, v) = r such that d (x, v) = d (x, y) − r. | wikipedia |
75bb690bf489387b12a94a626e2a6b5bf21b1877 | note that the inequality above for | f | note that the inequality above for | f s (y) − f t (y) | {\displaystyle |f_{s}(y)-f_{t}(y)|} (together with its proof) also holds for geodesic segments: if γ (t) is a geodesic segment starting at x and parametrised by arclength then | wikipedia |
311c6903d813a9d8b42e013ba49a1d4e0f456123 | let h (t) = d (y,γ(t)) − t | let h (t) = d (y,γ(t)) − t = f (y). since γ (t) {\displaystyle \gamma (t)} is parametrised by arclength, alexandrov's first comparison theorem for hadamard spaces implies that the function g (t) = d (y,γ(t)) − t is convex. hence for 0< s < t | wikipedia |
f0cf3dab39cd16981adac5c1621a27a2443ecb2f | in a hadamard space, where any two points | in a hadamard space, where any two points are joined by a unique geodesic segment, the function f = f t {\displaystyle f=f_{t}} is convex, i.e. convex on geodesic segments {\displaystyle }. explicitly this means that if z (s) {\displaystyle z(s)} is the point which divides {\displaystyle } in the ratio s : (1 − s), the... | wikipedia |
c79cb1782c625060ad8b5dd8fdb5845c3528348a | where the term in brackets on the right | where the term in brackets on the right hand side is the poisson kernel for the unit disk and ζ {\displaystyle \zeta } corresponds to the radial geodesic γ {\displaystyle \gamma } from the origin towards ζ {\displaystyle \zeta }, γ (t) = ζ tanh (t / 2) {\displaystyle \gamma (t)=\zeta \tanh(t/2)}. the computation of d (... | wikipedia |
fad45188ff373924c31882a810033d8424227fc9 | by dini's theorem, the functions f t (x) | by dini's theorem, the functions f t (x) = d (x, γ (t)) − t {\displaystyle f_{t}(x)=d(x,\gamma (t))-t} tend to b γ (x) {\displaystyle b_{\gamma }(x)} uniformly on compact sets as t tends to infinity. | wikipedia |
17eb8593465869597c2b80aae3462a1062414a95 | thus, when t is very large, the distance | thus, when t is very large, the distance d (γ (t), x) {\displaystyle d{\big (}\gamma (t),x{\big)}} is approximately equal to b γ (x) + t {\displaystyle b_{\gamma }(x)+t}. given a ray γ, its busemann function is always well-defined: indeed the right hand side above f t (x) = def d (γ (t), x) − t {\displaystyle f_{t}(x){... | wikipedia |
90c57b1506e09681869861e75b0da844dd47ca59 | let (x, d) {\displaystyle (x,d)} be a metric | let (x, d) {\displaystyle (x,d)} be a metric space. a geodesic ray is a path γ: [ 0, ∞) → x {\displaystyle \gamma :[0,\infty)\to x} which minimizes distance everywhere along its length. i.e., for all t, t ′ ∈ [ 0, ∞) {\displaystyle t,t'\in [0,\infty)}, | wikipedia |
d8acb88d694e8c674713f5a5f285b2059b6bc9c8 | in geometric topology, busemann functions are used to | in geometric topology, busemann functions are used to study the large-scale geometry of geodesics in hadamard spaces and in particular hadamard manifolds (simply connected complete riemannian manifolds of nonpositive curvature). they are named after herbert busemann, who introduced them; he gave an extensive treatment ... | wikipedia |
21183507adcaf7430da0b661ba0a02a558d2db4e | the bridge at nimreh is a roman bridge | the bridge at nimreh is a roman bridge in the vicinity of shahba, syria, dating to the 3rd or 4th century ad. its transversal arch construction derives from old building traditions of the hauran region and is arguably unique in roman bridge building. | wikipedia |
38a4441b9c345239fa39561ec377252c3ad0aaa1 | presumably, the bridge was built directly onto the | presumably, the bridge was built directly onto the solid stone. its almost unadorned masonry walls consist of rectangular, roughly smoothed basalt blocks of varying size without mortar (opus quasi-quadratum). since roman bridges rarely featured basalt, its use is undoubtedly due to the availability of the material in s... | wikipedia |
7f94ce36a21686e6bf52f2eb4dfeec110309271a | the vault was made of three parallel, transversal | the vault was made of three parallel, transversal arches standing at intervals of 1.20 m; the arches were built of 60 cm long, 30 cm wide and just as high ashlar, while the spaces in between are covered with longish basalt blocks. this design principle – transversal arches with lintels – seems to be unique among roman ... | wikipedia |
994e912cd4064bf7da9bff52051764cf5f2b808f | the bridge is situated 10 km southeast from | the bridge is situated 10 km southeast from shahba, close to the modern road at the foot of the mountain village nimreh, which was known in the onomastikon of eusebius by the name namara and regarded as an important place (vicus grandis). here, the bridge crosses the wadi al-liwa almost right-angled, making a small ben... | wikipedia |
0f9a34356b6841f93300598ebf5d6591e646ae0b | after the annexation by emperor trajan in 106 | after the annexation by emperor trajan in 106 ad, the infrastructure of the newly established provincia arabia was greatly expanded by the construction of roman forts and military roads to ward off nomadic incursions; in bostra the legio iii cyrenaica was stationed. the rugged terrain, with many wadis crisscrossing it,... | wikipedia |
9d804d7c456751473044c4304758d89b2c05f80b | the bridge at nimreh is located in the | the bridge at nimreh is located in the hauran (ancient name: auranitis), a mountainous volcanic region c. 80 km southeast from damascus in the transitional zone between agricultural land and the desert. due to fertile soils and sufficient rainfalls, the area yielded in roman times particularly high returns, which could... | wikipedia |
580f5c44d307c3709cf639e9fb6d84c7d4856560 | the bridge at nimreh is a roman bridge | the bridge at nimreh is a roman bridge in the vicinity of shahba (ancient philippopolis), syria, dating to the 3rd or 4th century ad. its transversal arch construction derives from old building traditions of the hauran region and is arguably unique in roman bridge building. | wikipedia |
ec3467bc51522a3720290b43d8e720f593429ba9 | brochosomes are intricately structured microscopic granules secreted by | brochosomes are intricately structured microscopic granules secreted by leafhoppers and typically found on their body surface and, more rarely, eggs. brochosomes were first described in 1952 with the aid of an electron microscope. brochosomes are hydrophobic and help keep the insect cuticle clean. these particles have ... | wikipedia |
877ec8086e86bf6a63d792b35ba87975a84235c2 | in several new world genera of the leafhopper | in several new world genera of the leafhopper subfamily cicadellinae (including the glassy-winged sharpshooter and related species) brochosomes are also used as a coating on egg masses. in gravid females from these genera, the malpighian tubules switch over from production of regular brochosomes, described above, to pr... | wikipedia |
f11ddb48c9b827e90a62a822152e543cc20d39fc | after each molt, most leafhopper species release droplets | after each molt, most leafhopper species release droplets of the brochosome-containing fluid through the anus and actively spread them over the newly formed integument. this behavior is called anointing. dry brochosomes are further distributed across the body and appendages in repeated bouts of grooming, in which leafh... | wikipedia |
04f8de0f60dadd33fef400f716c7ded89c996b90 | brochosomes are produced within cells of specialized glandular | brochosomes are produced within cells of specialized glandular segments of the malpighian tubules – the primary excretory organs of insects, which often serve additional functions. each cell simultaneously manufactures a large number of brochosomes within its golgi complexes and eventually releases them into the lumen ... | wikipedia |
d43d97267065776374b54521685ce232a76876b9 | most species of leafhoppers produce hollow spherical brochosomes, | most species of leafhoppers produce hollow spherical brochosomes, 0.2–0.7 micrometres in diameter, with a honeycombed outer wall. they often consist of 20 hexagonal and 12 pentagonal cells, making the outline of each brochosome approximating a truncated icosahedron – the geometry of a soccer ball and a c buckminsterful... | wikipedia |
af1ea011e8dce091402571e325e77e66935c7d87 | brochosomes are intricately structured microscopic granules secreted by | brochosomes are intricately structured microscopic granules secreted by leafhoppers (the family cicadellidae of the insect order hemiptera) and typically found on their body surface and, more rarely, eggs. brochosomes were first described in 1952 with the aid of an electron microscope. brochosomes are hydrophobic and h... | wikipedia |
be18f4819b069027c3c259816413cc4e018a44d1 | cleidson rodrigues dos santos or simply cleidson is | cleidson rodrigues dos santos or simply cleidson is a brazilian footballer who plays primarily as a left back. he currently plays for itumbiara esporte clube. a strong, versatile player who can deputise at centre back should the need arise, cleidson was linked with several european clubs during the 2012 summer transfer... | wikipedia |
e12c5ff675562275887eb9fabc7218100beded80 | a strong, versatile player who can deputise at | a strong, versatile player who can deputise at centre back should the need arise, cleidson was linked with several european clubs during the 2012 summer transfer window: most notably vfb stuttgart of the german bundesliga as well as queens park rangers and swansea city, then both of the english premier league. | wikipedia |
f39ce10e9e358b28dd11b75139e6b5e21f394c62 | cleidson rodrigues dos santos or simply cleidson (born | cleidson rodrigues dos santos or simply cleidson (born 13 august 1988) is a brazilian footballer who plays primarily as a left back. he currently plays for itumbiara esporte clube. | wikipedia |
85739f92f29b7e855a8472bc6c617d50a2653b93 | dean edward martin is an english football manager, | dean edward martin is an english football manager, coach and former player who is assistant coach of Ía. a midfielder, martin spent much of his playing career in iceland with ka and Ía and he also played in england, hong kong and the republic of ireland. he moved into coaching and management whilst still a player and h... | wikipedia |
74a3801b0687cf8707151715187ba0604c5a9bef | in international football, martin has assisted and coached | in international football, martin has assisted and coached iceland at youth level and in january 2017 he was appointed the ksÍ's head of talent identification. he departed his roles to become assistant manager of china women in november 2017, but he left the setup after manager sigurður ragnar eyjólfsson was sacked in ... | wikipedia |
a59d902f45d63cad94d555d450253ccdcb3c698c | martin completed his ksÍ 'a' coaching badges in | martin completed his ksÍ 'a' coaching badges in 2009 and has a bsc in sports science from reykjavík university. he has held management roles at ka, breiðablik u19 and hk u19. he has worked as an assistant manager at club sides Ía, Íbv and hk. on 26 september 2018, martin was appointed as manager of newly-relegated 2. d... | wikipedia |
51f1b330ba19e95f3e23e415b82593173a6848ab | between 1995 and 2001, martin spent the autumn | between 1995 and 2001, martin spent the autumn and winter months playing for clubs outside iceland. he returned to england to play for brentford (1995–96), hereford united (1998–99) and stevenage borough during the 1999–00 and 2000–01 seasons. he also played in hong kong for eastern aa and hong kong rangers and in the ... | wikipedia |
6384d988e1b25421db7924327baf3e262ac73bd3 | martin moved to iceland to join 1. deild | martin moved to iceland to join 1. deild karla club ka in 1995. martin's icelandic career stretched from 1995 to 2014 and he played in the top two divisions, principally for ka and Ía. he won a promotion from the 1. deild karla with each club and played european football for both. martin retired at age 42, after spendi... | wikipedia |
7eed3dbe875249c2539a05d34d6e3665b4bd1913 | a midfielder, martin began his career in sunday | a midfielder, martin began his career in sunday league football, before moving to conference club fisher athletic. he returned to first division club west ham united, with whom he had spent a period as a youth, for a £25,000 fee in may 1991. martin made three appearances during the second half of the 1991–92 season, wh... | wikipedia |
5fd0a50f6de174ee7c1da2822183d9e5bb3eb632 | a midfielder, martin spent much of his playing | a midfielder, martin spent much of his playing career in iceland with ka and Ía and he also played in england, hong kong and the republic of ireland. he moved into coaching and management whilst still a player and has held senior and youth roles with club and international teams in iceland. | wikipedia |
739df42b7f12b5f0947617ba7d9aff15277afed2 | notation: | x ⟩ - position eigenstate | | notation: | x ⟩ - position eigenstate | α ⟩ , | β ⟩ , | γ ⟩ . . . - wave function of the state of the system Ψ - total wave function of a system ψ - wave function of a system ψ α - wave function of a particle in position representation, equal to ⟨ x | α ⟩ | wikipedia |
ba795f8b506559c1bd60dce2e9712b48e9ee2e53 | it can be derived from (1) by considering | it can be derived from (1) by considering Ψ α (x, t):= ⟨ x | α ⟩ {\displaystyle \psi _{\alpha }(x,t):=\langle x|\alpha \rangle } and h ^:= − ℏ 2 2 m ∇ 2 + v ^ {\displaystyle {\hat {h}}:=-{\frac {\hbar ^{2}}{2m}}\nabla ^{2}+{\hat {v}}} | wikipedia |
8245cc2226b9cf039b7f97a5e7f61eb08ef2392f | calvin blackman bridges was an american scientist known | calvin blackman bridges was an american scientist known for his contributions to the field of genetics. along with alfred sturtevant and h.j. muller, bridges was part of thomas hunt morgan's famous "fly room" at columbia university. | wikipedia |
745e4a529f26344f1ce46b1fddc0e06f9daa0842 | 2. muhlrad, paul j. "fruit fly: drosophila." genetics. | 2. muhlrad, paul j. "fruit fly: drosophila." genetics. ed. richard robinson. vol. 2. new york: macmillan reference usa, 2003. 42-45. gale virtual reference library. web. 26 january 2015. | wikipedia |
40e8516f1f1b5d2e48b2c5351373809a7819bd4a | 1. "bridges, calvin blackman." complete dictionary of scientific | 1. "bridges, calvin blackman." complete dictionary of scientific biography. vol. 2. detroit: charles scribner's sons, 2008. 455-457. gale virtual reference library. web. 26 january 2015. | wikipedia |
7978610430f9e41cd0f2340b64849b22d2bbab74 | bridges married gertrude ives, with whom he had | bridges married gertrude ives, with whom he had four children. he was known to be both brilliant and very kind and considerate, though he was equally well-known for his womanizing and his struggles to keep up with family obligations. he was an atheist. in 1938, bridges died from what is believed to have been a case of ... | wikipedia |
6c18dc81c46b1556ebba0ab86850d21365fcc0f9 | after his death, bridges' student katherine brehme warren | after his death, bridges' student katherine brehme warren completed work on the mutants of drosophila melanogaster (1944), a classic book which was for two decades an indispensable resource for geneticists, with information from the "red book" later being transferred to the flybase database. morgan and sturtevant destr... | wikipedia |
18d9ed4b33b036e94b0ae17444826fd35f11cf65 | bridges' phd thesis on " non-disjunction as proof | bridges' phd thesis on " non-disjunction as proof of the chromosome theory of heredity" appeared as the first paper in the first issue of the journal genetics in 1916. in this paper, he also established that the y chromosome does not determine gender in drosophila. bridges' best-known contribution among drosophila rese... | wikipedia |
9f118a2fd7e2ea0a0706239f15112c70ac8aa37d | bridges published many works, one of his most | bridges published many works, one of his most famous being "sex in relation to chromosomes and genes". he also contributed many items to the journal of experimental zoology and science. his work with sex-linked traits suggested that chromosomes contained genes; nettie maria stevens was later able to support this hypoth... | wikipedia |
2f9f0c9f5556295765c138308df52202ab217275 | bridges in particular was responsible for many improvements | bridges in particular was responsible for many improvements regarding the techniques and the equipment used in the experiments. he suggested the use binocular microscopes instead of hand lenses that had been using before, which improved data quality and convenience. bridges also developed temperature controls for the e... | wikipedia |
0bc08ed9f7edd9c7d764eda16079fe8e40127665 | the "fly room" experiments began in 1910 and | the "fly room" experiments began in 1910 and continued for seventeen years, with thomas hunt morgan being the project's lead experimental developer. among many others working alongside bridges and morgan in the laboratory were alfred sturtevant and hermann joseph muller. the "fly room" experiments were the first to use... | wikipedia |
6e0da03e44b6ad3dafa7f50a1c7857040cb23a93 | calvin blackman bridges was born in schuyler falls, | calvin blackman bridges was born in schuyler falls, new york in 1889 to the parents of leonard bridges and charlotte blackman. tragically, calvin's mother died when he was two years old, and his father died a year later, leaving the young calvin an orphan. bridges was subsequently taken in and raised by his grandmother... | wikipedia |
16517200685c859789ea6ca53deb621abf7290a0 | calvin blackman bridges (january 11, 1889 – december | calvin blackman bridges (january 11, 1889 – december 27, 1938) was an american scientist known for his contributions to the field of genetics. along with alfred sturtevant and h.j. muller, bridges was part of thomas hunt morgan 's famous "fly room" at columbia university. | wikipedia |
dba4c118cf50ded8906c22433eafbb9b2628b256 | the bristol cherub is a british two-cylinder, air-cooled, | the bristol cherub is a british two-cylinder, air-cooled, aircraft engine designed and built by the bristol aeroplane company. introduced in 1923 it was a popular engine for ultralight and small aircraft in the 1930s. | wikipedia |
dba4c118cf50ded8906c22433eafbb9b2628b256 | the bristol cherub is a british two-cylinder, air-cooled, | the bristol cherub is a british two-cylinder, air-cooled, aircraft engine designed and built by the bristol aeroplane company. introduced in 1923 it was a popular engine for ultralight and small aircraft in the 1930s. | wikipedia |
e831e911e84e3169ee3601cad13cd5e90baa716f | conor ramsay is a scottish professional footballer who | conor ramsay is a scottish professional footballer who plays for arthurlie in the scottish junior football association, west region. he is a former scotland youth international and has previously played in the scottish premier league for st mirren. | wikipedia |
17dc99c460e12584399564dba3e3c25b052bfbf4 | a midfielder, ramsay started his career with hometown | a midfielder, ramsay started his career with hometown team st mirren. he made five appearances in the scottish premier league under the management of gus macpherson at the age of sixteen while also featuring for the scotland u17 international team. injury restricted his progress at st mirren and ramsay moved to rivals ... | wikipedia |
e3315a16b192d0bf5a725fff254b4b3a9b445009 | conor ramsay (born 9 march 1993) is a | conor ramsay (born 9 march 1993) is a scottish professional footballer who plays for arthurlie in the scottish junior football association, west region. he is a former scotland youth international and has previously played in the scottish premier league for st mirren. | wikipedia |
9e88f4bad434697ba5f0619b5bf72256ad645f94 | gudrun kadereit is a german botanist, the princess | gudrun kadereit is a german botanist, the princess therese von bayern chair of systematics, biodiversity and evolution of plants at the ludwig maximilians university of munich and the director of both the botanical garden munich-nymphenburg and the botanical state collection munich. | wikipedia |
3a58b46288152ef1de2937b4496ae26cf302c993 | her research focuses on angiosperm phylogenetics, systematics and | her research focuses on angiosperm phylogenetics, systematics and biogeography, in particular on the families amaranthaceae, melastomataceae, crassulaceae, aizoaceae and zygophyllaceae but also on the evolution of c4 photosynthesis and crassulacean acid metabolism (cam) and the evolution of seed traits. | wikipedia |
f857b8566b445e7a375265bc093ce91116730780 | gudrun kadereit (born 1969) is a german botanist, | gudrun kadereit (born 1969) is a german botanist, the princess therese von bayern chair of systematics, biodiversity and evolution of plants at the ludwig maximilians university of munich and the director of both the botanical garden munich-nymphenburg and the botanical state collection munich. her research focuses on ... | wikipedia |
4ff95e1b5e87d6ae1ac5006aca4745c44cb710a4 | branko grünbaum was a croatian-born mathematician of jewish | branko grünbaum was a croatian-born mathematician of jewish descent and a professor emeritus at the university of washington in seattle. he received his ph.d. in 1957 from hebrew university of jerusalem in israel. | wikipedia |
635957ea6dfd7796face1727f8817207cd422e31 | in 1976 grünbaum won a lester r. ford | in 1976 grünbaum won a lester r. ford award for his expository article venn diagrams and independent families of sets. in 2004, gil kalai and victor klee edited a special issue of discrete and computational geometry in his honor, the "grünbaum festschrift". in 2005, grünbaum was awarded the leroy p. steele prize for ma... | wikipedia |
778eda38e739a2fff229e9bd3b5a2073c0452170 | grünbaum's classic monograph convex polytopes, first published in | grünbaum's classic monograph convex polytopes, first published in 1967, became the main textbook on the subject. his monograph tilings and patterns, coauthored with g. c. shephard, helped to rejuvenate interest in this classic field, and has proved popular with nonmathematical audiences, as well as with mathematicians. | wikipedia |
dde9737d9c3c4312bb9e73883a4d1a224c0d3797 | his paper on line arrangements may have inspired | his paper on line arrangements may have inspired a paper by n. g. de bruijn on quasiperiodic tilings (the most famous example of which is the penrose tiling of the plane). this paper is also cited by the authors of a monograph on hyperplane arrangements as having inspired their research. | wikipedia |
2d869126d24c5bce5d87668c7cbf6305069db68a | grünbaum remained affiliated with the hebrew university until | grünbaum remained affiliated with the hebrew university until 1966, taking long research visits to the university of washington and in 1965–1966 to michigan state university. however, during the michigan visit, learning of another case similar to their marriage annulment, he and zdenka decided to stay in the us instead... | wikipedia |
c52d713cdec45557363d3abc26a2f013d55cfe74 | after finishing his military service in 1958, grünbaum | after finishing his military service in 1958, grünbaum and his family came to the us so that grünbaum could become a postdoctoral researcher at the institute for advanced study. he then became a visiting researcher at the university of washington in 1960. he agreed to return to israel as a lecturer at the hebrew univer... | wikipedia |
ba730828329606a57096ff321580470b93be89df | in israel, grünbaum found a job in tel | in israel, grünbaum found a job in tel aviv, but in 1950 returned to the study of mathematics, at the hebrew university of jerusalem. he earned a master's degree in 1954 and in the same year married zdenka, who continued as a master's student in chemistry. he served a tour of duty as an operations researcher in the isr... | wikipedia |
c38e5473372a18a45cf4bfb0132634afd3e0fbad | grünbaum was born in osijek, then part of | grünbaum was born in osijek, then part of the kingdom of yugoslavia, on 2 october 1929. his father was jewish and his mother was catholic, so during world war ii the family survived the holocaust by living at his catholic grandmother's home. after the war, as a high school student, he met zdenka bienenstock, a jew who ... | wikipedia |
c28a10b98ff481658a3604d7f7544d9a121c26f4 | branko grünbaum (hebrew: ברנקו גרונבאום; 2 october 1929 | branko grünbaum (hebrew: ברנקו גרונבאום; 2 october 1929 – 14 september 2018) was a croatian-born mathematician of jewish descent and a professor emeritus at the university of washington in seattle. he received his ph.d. in 1957 from hebrew university of jerusalem in israel. | wikipedia |
49553a05860ff0431b88d8710971858cfc42aa32 | joseph hector "hec" lépine was a canadian professional | joseph hector "hec" lépine was a canadian professional ice hockey forward who played 33 games in the national hockey league for the montreal canadiens during the 1925–26 season. the rest of his career, which lasted from 1917 to 1927, was spent in minor leagues. he was born in sainte-anne-de-bellevue, quebec. hector is ... | wikipedia |
3e7394c1310019f7fa984daead0bb76ddeb835c4 | joseph hector "hec" lépine (december 7, 1897 — | joseph hector "hec" lépine (december 7, 1897 — march 29, 1951) was a canadian professional ice hockey forward who played 33 games in the national hockey league for the montreal canadiens during the 1925–26 season. the rest of his career, which lasted from 1917 to 1927, was spent in minor leagues. he was born in sainte-... | wikipedia |
44dc5fa18dbfa19075c0752aabbf75f8e9acf86c | in mathematics, a higher spin alternating sign matrix | in mathematics, a higher spin alternating sign matrix is a generalisation of the alternating sign matrix (asm), where the columns and rows sum to an integer r rather than simply summing to 1 as in the usual alternating sign matrix definition. hsasms are square matrices whose elements may be integers in the range −r to ... | wikipedia |
45fa579977c9c3c3ea91a8cbe0981ace5b2aa0dd | in mathematics, a higher spin alternating sign matrix | in mathematics, a higher spin alternating sign matrix is a generalisation of the alternating sign matrix (asm), where the columns and rows sum to an integer r (the spin) rather than simply summing to 1 as in the usual alternating sign matrix definition. hsasms are square matrices whose elements may be integers in the r... | wikipedia |
9a6b01a9da74fed65627038dd17f4ec0232fb617 | smith joined convair in 1941, working extensively in | smith joined convair in 1941, working extensively in the area of fatigue with a focus on aluminum aircraft structures. he contributed work on fatigue in support of the us air force, us navy, and nasa. smith was an early adopter of photoelasticity to determining stress concentrations due to notches, corner fillets, and ... | wikipedia |
867c43833bf575bb1c4f6936c4481aba61120de8 | assuming that the bully algorithm messages are of | assuming that the bully algorithm messages are of a fixed (known, invariant) sizes, the most number of messages are exchanged in the group when the process with the lowest id initiates an election. this process sends (n−1) election messages, the next higher id sends (n−2) messages, and so on, resulting in Θ (n 2) {\dis... | wikipedia |
2641415f02bed88549d205eedccf6f9fb4a5b03e | liveness is also guaranteed in the synchronous, crash-recovery | liveness is also guaranteed in the synchronous, crash-recovery model. consider the would-be leader failing after sending an answer (alive) message but before sending a coordinator (victory) message. if it does not recover before the set timeout on lower id processes, one of them will become leader eventually (even if s... | wikipedia |
d4e1b6ce6bf8584eea17c438a4524023e0a9d435 | the safety property expected of leader election protocols | the safety property expected of leader election protocols is that every non-faulty process either elects a process q, or elects none at all. note that all processes that elect a leader must decide on the same process q as the leader. the bully algorithm satisfies this property (under the system model specified), and at... | wikipedia |
e8f9005ca67c41b7944a2ef735f771e280fa4fc3 | in public key cryptography, a certificate may be | in public key cryptography, a certificate may be revoked before it expires, which signals that it is no longer valid. without revocation, an attacker could exploit such a compromised or misissued certificate until expiry. hence, revocation is an important part of a public key infrastructure. revocation is performed by ... | wikipedia |
50a3e0e888b996fd1685e5ba2c08fa242ebf299b | private information retrieval techniques can allay the privacy | private information retrieval techniques can allay the privacy concern with pull-based checks. rather than clients performing revocation checks, a middlebox could instead, centralising the cost of revocation checking and amortising it across many connections; the clients need to dedicate no storage to revocation inform... | wikipedia |
e2a2e911b30ef637e4ffda8bef4a56fae7f8c526 | let's revoke has not yet been widely deployed. | let's revoke has not yet been widely deployed. besides client implementations, it requires cas to make operational changes, and does not provide as much information as crls or ocsp (only a bit per certificate for validity); crls or ocsp may still be used to supplement let's revoke and provide that additional informatio... | wikipedia |
d2531fc0e3c5779ce4088a2af6f95d03c6bd2d00 | crvs are expected to be small enough to | crvs are expected to be small enough to enable push-based checking, but more constrained clients may still perform pull-based checks, only accessing select crvs, or deferring retrieval of crvs until certificate validation. a client using let's revoke with push-based checking is able to fail-hard for any certificate wit... | wikipedia |
5904392da925f7946be335f0e38b05573f7387fb | let's revoke uses bit vectors of revocation statuses | let's revoke uses bit vectors of revocation statuses (called certificate revocation vectors, or crvs) to allow large amounts of revocation statuses to be efficiently retrieved by clients. cas generate crvs for their own certificates, with one crv per expiration date. crv maintenance for cas is linear in the number of c... | wikipedia |
8b6ebb64acd1f9d324bf4b86d1d682745ab4115c | crlite has not yet been widely deployed. it | crlite has not yet been widely deployed. it is, however, deployable, only requiring an aggregator to retrieve crls from cas and then provide the filter cascade and updates to it, and for clients to use it; no action from cas is needed, and nor is any needed from certificate holders. the aggregator does not need to be a... | wikipedia |
9034c76e3bdb831778843e9e91a24648738ddb9e | the revocation status of all certificates in the | the revocation status of all certificates in the web pki in january was estimated to be 10 mb in size when using the bloom filter cascade, with updates of 580 kb per day. in march 2018, this had grown to 18 mb. in a simulation with 100 million certificates, a 1% daily expiration rate, and a 2% revocation rate, crlite r... | wikipedia |
50186713fe28a7ec93fc77c19e2b024c4aa0c015 | crlite provides revocation statuses by a cascade of | crlite provides revocation statuses by a cascade of bloom filters. a single filter constructed from a list of revoked certificates produces false positives. with an open domain, this is an insuperable problem for revocation checking. however, by using certificate transparency to enumerate all unexpired certificates, an... | wikipedia |
a30e933c9a15ab36aafcb8542a178551e982d5b5 | beyond clients and cas enabling stapling and the | beyond clients and cas enabling stapling and the must-staple extension, server administrators must also take action to support stapling by regularly retrieving responses and then providing them to clients during the handshake. in 2018, only firefox supported must-staple, and neither of the two most-used web servers (ap... | wikipedia |
8d2f370bbbca47faf4b8bb1e5bcf940460c40695 | ocsp stapling can solve the operational challenges of | ocsp stapling can solve the operational challenges of ocsp, namely additional network requests causing latency and privacy degradation. however, it can be susceptible to downgrade attacks by an on-path attacker. rfc 7633 defines an extension that embeds a requirement into a certificate to be stapled to a valid ocsp res... | wikipedia |
22e892fd5c625c6075f0f6828ee03f26e4fb5991 | a 2018 study found that 1.7% of requests | a 2018 study found that 1.7% of requests to responders were unavailable at the network level, and a further c. 2% produced unusable ocsp responses, with significant hetereogeneity across cas and client vantage points. | wikipedia |
6bdf1916ea6b68082753ea89d2345d6bbcc82294 | as requests to the responder are made in | as requests to the responder are made in response to users' browsing, ocsp responders can learn about the users' browsing, which is a privacy issue. it also introduces latency to connections, as the responder must be queried before a new connection can be used. | wikipedia |
b40e9f4189fea075c7e1a453e46aeb47ae9bbfe3 | ocsp suffers from scalability issues. it relies on | ocsp suffers from scalability issues. it relies on the client having network access at the time of checking the certificate's revocation status; further, the ocsp responder must be accessible and produce usable responses, or else the check will fail and the client must choose between failing-soft and failing-hard. many... | wikipedia |
9fae1769b0ea55e0de9aa675aa8e4fcecb41697d | the online certificate status protocol (ocsp) allows clients | the online certificate status protocol (ocsp) allows clients to interactively ask a server (an ocsp responder) about a certificate's status, receiving a response that is cryptographically authenticated by the issuing ca. it was designed to address issues with crls. a typical ocsp response is less than 1 kb. | wikipedia |
4a88121f133d39af7c4c11cb81045edde35d7753 | a crl contains information about all of the | a crl contains information about all of the certificates revoked by a ca, which means distributors and clients must incur transfer costs for information that is likely irrelevant. a 2015 study found that the median certificate had a crl with size 51 kb, and the largest crl was 76 mb. | wikipedia |
0a127234508b18e3d8237585d508d836947fd4b1 | push-based checking is less bandwidth efficient than pull-based | push-based checking is less bandwidth efficient than pull-based checking, but gains availability and privacy. different methods may be used on a certificate-by-certificate basis, allowing for fine-tuning the trade-off: both google chrome and mozilla firefox perform push-based checks on a small set of critical certifica... | wikipedia |
1a593d68cbed665fcfb5a7cc9263e8249c22c6db | there are three broad architectures for how clients | there are three broad architectures for how clients access revocation status: pull-based, where clients retrieve revocation status at validation time; push-based, where clients retrieve revocation status ahead of validation and cache it; and network-assisted, where revocation checking is tightly integrated with the tls... | wikipedia |
8b4e415815bf0522677f01eeb89283ce34bffbe2 | a revocation status distribution that places heavy burdens | a revocation status distribution that places heavy burdens on cas may not succeed, especially if the ca is unable to derive countervailing benefits from implementation. reducing the number of parties that must make changes to adopt it also eases deployability: potentially involved are cas, clients, server administrator... | wikipedia |
17d8398a3e72be9da9f18f5865a9374bdd58da28 | if revocation status is not freshly retrieved for | if revocation status is not freshly retrieved for every check (e.g., due to caching or periodic retrievals), there is a delay between a certificate being revoked and all clients being guaranteed to be aware of the revocation. this presents a trade-off between latency, efficiency, and security: longer cache times or les... | wikipedia |
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