Create model.py

model.py

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+"""
+PentachoraViT: Vision Transformer with Pentachoron Geometric Structure
+Enhanced with Geometric Attention for improved head cohesion and generalization
+"""
+
+import torch
+import torch.nn as nn
+import torch.nn.functional as F
+import numpy as np
+from einops import rearrange, repeat
+import math
+from typing import Optional, Dict, Tuple, List, Any
+from dataclasses import dataclass
+import warnings
+
+# ============================================
+# CONFIGURATION CLASSES
+# ============================================
+
+@dataclass
+class PentachoraConfig:
+    """Configuration for PentachoraViT models."""
+    img_size: int = 32
+    patch_size: int = 4
+    num_classes: int = 100
+    dim: int = 512
+    vocab_dim: Optional[int] = None  # Vocabulary dimension (can differ from model dim)
+    depth: int = 12
+    heads: int = 8
+    mlp_ratio: float = 4.0
+    use_mesh_attention: bool = True
+    preserve_structure_until_layer: int = 6
+    dropout_rate: float = 0.1
+    drop_path_rate: float = 0.1
+    aux_loss_weight: float = 0.3
+    geo_loss_weight: float = 0.1
+    vocab: Optional[Any] = None
+    
+    @property
+    def num_patches(self) -> int:
+        return (self.img_size // self.patch_size) ** 2
+
+# ============================================
+# GEOMETRIC ATTENTION COMPONENTS
+# ============================================
+
+def perfect_4simplex(device):
+    """Create perfect 4-simplex (pentachoron) vertices in 4D."""
+    sqrt5 = math.sqrt(5)
+    vertices = torch.tensor([
+        [1, 1, 1, -1/sqrt5],
+        [1, -1, -1, -1/sqrt5],
+        [-1, 1, -1, -1/sqrt5],
+        [-1, -1, 1, -1/sqrt5],
+        [0, 0, 0, 4/sqrt5]
+    ], device=device, dtype=torch.float32)
+    return vertices / 2  # Normalize scale
+
+def softmin_over_last(distances, tau):
+    """Softmin over last dimension."""
+    return F.softmax(-distances / tau, dim=-1).sum(dim=-1)
+
+@dataclass
+class GeometricConfig:
+    """Configuration for geometric attention."""
+    softmin_tau: float = 0.05
+    fuse_alpha: float = 0.7
+    phases: Tuple[float, ...] = (0.0, math.pi/2, math.pi, 3*math.pi/2)
+    jitter: float = 0.02
+    shift: float = 0.25
+    rotate_cycle: int = 11
+    use_phase_variance: bool = False
+    geometry_type: str = "pentachoron"
+
+class GeometricNavigator(nn.Module):
+    """Maps inputs to geometric regions in 4D space."""
+    
+    def __init__(self, input_dim: int, num_regions: int, config: GeometricConfig):
+        super().__init__()
+        self.input_dim = input_dim
+        self.num_regions = num_regions
+        self.config = config
+        
+        self.to_nav = nn.Linear(input_dim, 4, bias=False)
+        self.vertex_w = nn.Parameter(torch.zeros(num_regions, 5))
+        
+        # Initialize geometry after module is created
+        self.register_parameter('D', None)
+        self.register_parameter('S', None)
+    
+    def _lazy_init_geometry(self, device):
+        """Initialize geometry on first forward pass."""
+        if self.D is not None:
+            return
+            
+        base = perfect_4simplex(device)
+        
+        D = torch.zeros(self.num_regions, 5, 4, device=device)
+        S = torch.zeros(self.num_regions, 5, 4, device=device)
+        
+        for r in range(self.num_regions):
+            D[r] = base + self.config.jitter * torch.randn_like(base)
+            
+            theta = torch.tensor(0.27 + 0.05 * (r % self.config.rotate_cycle), device=device)
+            rot = torch.eye(4, device=device)
+            c, s_val = torch.cos(theta), torch.sin(theta)
+            rot[0, 0] = c; rot[0, 1] = -s_val
+            rot[1, 0] = s_val; rot[1, 1] = c
+            S[r] = (base @ rot) + self.config.shift
+            S[r] += self.config.jitter * torch.randn_like(S[r])
+        
+        self.D = nn.Parameter(D)
+        self.S = nn.Parameter(S)
+    
+    def navigate(self, x: torch.Tensor) -> Dict[str, torch.Tensor]:
+        """Navigate inputs through geometric space."""
+        self._lazy_init_geometry(x.device)
+        
+        nav_x = self.to_nav(x)
+        nav_x_exp = nav_x[:, None, None, :]
+        D_exp = self.D[None, :, :, :]
+        
+        d_disp = torch.norm(nav_x_exp - D_exp, dim=-1)
+        s_disp = -softmin_over_last(d_disp, self.config.softmin_tau)
+        
+        w = F.softmax(self.vertex_w, dim=1)
+        phase_scores = []
+        
+        for phase in self.config.phases:
+            phase_tensor = torch.tensor(phase, device=x.device)
+            ct = torch.cos(phase_tensor)
+            st = torch.sin(phase_tensor)
+            
+            Vt = ct * self.D + st * self.S
+            w_expanded = w.unsqueeze(-1)
+            Vt_mean = Vt.mean(dim=1, keepdim=True)
+            Vt = (1.0 - w_expanded) * Vt + w_expanded * Vt_mean
+            
+            Vt_exp = Vt[None, :, :, :]
+            d_ribbon = torch.norm(nav_x_exp - Vt_exp, dim=-1)
+            s_ribbon = -softmin_over_last(d_ribbon, self.config.softmin_tau)
+            phase_scores.append(s_ribbon)
+        
+        s_ribbon = torch.stack(phase_scores).mean(dim=0)
+        scores = self.config.fuse_alpha * s_ribbon + (1 - self.config.fuse_alpha) * s_disp
+        
+        diagnostics = {
+            'dispatcher_scores': s_disp.detach(),
+            'ribbon_scores': s_ribbon.detach()
+        }
+        
+        return {'scores': scores, 'diagnostics': diagnostics}
+
+class GeometricAttention(nn.Module):
+    """Multi-head geometric attention with Q-K alignment."""
+    
+    def __init__(self, dim: int, num_heads: int = 8, num_regions: Optional[int] = None,
+                 config: Optional[GeometricConfig] = None, dropout: float = 0.0):
+        super().__init__()
+        self.dim = dim
+        self.num_heads = num_heads
+        self.head_dim = dim // num_heads
+        
+        if num_regions is None:
+            num_regions = min(self.head_dim, 16)
+        if config is None:
+            config = GeometricConfig()
+        
+        self.config = config
+        self.to_qkv = nn.Linear(dim, dim * 3, bias=False)
+        
+        self.q_navigators = nn.ModuleList([
+            GeometricNavigator(self.head_dim, num_regions, config)
+            for _ in range(num_heads)
+        ])
+        self.k_navigators = nn.ModuleList([
+            GeometricNavigator(self.head_dim, num_regions, config)
+            for _ in range(num_heads)
+        ])
+        
+        self.out_proj = nn.Linear(dim, dim)
+        self.dropout = nn.Dropout(dropout)
+    
+    def forward(self, x: torch.Tensor, mask: Optional[torch.Tensor] = None,
+                return_diagnostics: bool = False) -> Tuple[torch.Tensor, Optional[Dict]]:
+        B, T, D = x.shape
+        
+        qkv = self.to_qkv(x)
+        q, k, v = qkv.chunk(3, dim=-1)
+        
+        q = q.reshape(B, T, self.num_heads, self.head_dim).transpose(1, 2)
+        k = k.reshape(B, T, self.num_heads, self.head_dim).transpose(1, 2)
+        v = v.reshape(B, T, self.num_heads, self.head_dim).transpose(1, 2)
+        
+        outputs = []
+        all_diagnostics = [] if return_diagnostics else None
+        
+        for h in range(self.num_heads):
+            q_h_flat = q[:, h].reshape(B * T, self.head_dim)
+            k_h_flat = k[:, h].reshape(B * T, self.head_dim)
+            
+            q_nav = self.q_navigators[h].navigate(q_h_flat)
+            k_nav = self.k_navigators[h].navigate(k_h_flat)
+            
+            q_scores = q_nav['scores'].reshape(B, T, -1)
+            k_scores = k_nav['scores'].reshape(B, T, -1)
+            
+            attn = torch.bmm(q_scores, k_scores.transpose(1, 2))
+            attn = attn / math.sqrt(q_scores.size(-1))
+            
+            if mask is not None:
+                attn = attn.masked_fill(mask.unsqueeze(1) == 0, -1e9)
+            
+            attn = F.softmax(attn, dim=-1)
+            attn = self.dropout(attn)
+            
+            out = torch.bmm(attn, v[:, h])
+            outputs.append(out)
+            
+            if return_diagnostics:
+                all_diagnostics.append({'q': q_nav['diagnostics'], 'k': k_nav['diagnostics']})
+        
+        output = torch.stack(outputs, dim=1).transpose(1, 2).reshape(B, T, D)
+        output = self.out_proj(output)
+        output = self.dropout(output)
+        
+        if return_diagnostics:
+            return output, {'head_diagnostics': all_diagnostics}
+        return output, None
+
+# ============================================
+# DROP PATH (STOCHASTIC DEPTH)
+# ============================================
+
+class DropPath(nn.Module):
+    """Drop paths (Stochastic Depth) per sample."""
+    def __init__(self, drop_prob: float = 0.):
+        super().__init__()
+        self.drop_prob = drop_prob
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        if self.drop_prob == 0. or not self.training:
+            return x
+        keep_prob = 1 - self.drop_prob
+        shape = (x.shape[0],) + (1,) * (x.ndim - 1)
+        random_tensor = keep_prob + torch.rand(shape, dtype=x.dtype, device=x.device)
+        random_tensor.floor_()
+        output = x.div(keep_prob) * random_tensor
+        return output
+
+# ============================================
+# HIERARCHICAL CLS WITH PENTACHORA
+# ============================================
+
+class HierarchicalPentachoronCLS(nn.Module):
+    """
+    Hierarchical CLS structure with pentachoron geometry.
+    Creates global, vertex-level, and class-specific representations.
+    """
+    def __init__(self, dim: int, vocab_dim: int, num_classes: int = 100):
+        super().__init__()
+        self.dim = dim  # Model's internal dimension
+        self.vocab_dim = vocab_dim  # Vocabulary's dimension
+        self.num_classes = num_classes
+        
+        # Hierarchical CLS tokens (in model dimension)
+        self.global_cls = nn.Parameter(torch.randn(1, 1, dim) * 0.02)
+        self.vertex_cls = nn.Parameter(torch.randn(1, 5, dim) * 0.02)
+        
+        # Class-specific pentachora (in vocabulary dimension)
+        self.class_pentachora = nn.Parameter(torch.randn(num_classes, 5, vocab_dim) * 0.02)
+        
+        # Projection layer to align vocab_dim with model dim if they differ
+        if vocab_dim != dim:
+            self.vocab_projection = nn.Linear(vocab_dim, dim)
+        else:
+            self.vocab_projection = nn.Identity()
+        
+        # Aggregation layers
+        self.vertex_to_global = nn.Linear(dim * 5, dim)
+        self.norm = nn.LayerNorm(dim)
+        
+    def forward(self, batch_size: int) -> Tuple[torch.Tensor, torch.Tensor]:
+        """Generate CLS tokens for batch."""
+        global_cls = self.global_cls.expand(batch_size, -1, -1)
+        vertex_cls = self.vertex_cls.expand(batch_size, -1, -1)
+        return global_cls, vertex_cls
+    
+    def aggregate_vertices(self, vertex_cls: torch.Tensor) -> torch.Tensor:
+        """Aggregate vertex representations to global."""
+        B = vertex_cls.shape[0]
+        flattened = vertex_cls.reshape(B, -1)
+        aggregated = self.vertex_to_global(flattened).unsqueeze(1)
+        return self.norm(aggregated)
+
+# ============================================
+# GEOMETRIC PROJECTION LAYER
+# ============================================
+
+class GeometricProjection(nn.Module):
+    """Project patches onto pentachoron geometry."""
+    def __init__(self, dim: int, vocab_dim: int, num_classes: int = 100, dropout: float = 0.1):
+        super().__init__()
+        self.dim = dim  # Model dimension
+        self.vocab_dim = vocab_dim  # Vocabulary dimension
+        self.num_classes = num_classes
+        
+        # Separate projection for each vertex (project from model dim to vocab dim for alignment)
+        self.vertex_projections = nn.ModuleList([
+            nn.Linear(dim, vocab_dim, bias=False) for _ in range(5)
+        ])
+        
+        self.norm = nn.LayerNorm(dim)
+        self.dropout = nn.Dropout(dropout)
+        
+    def forward(self, patches: torch.Tensor, pentachora: torch.Tensor) -> torch.Tensor:
+        """
+        Compute alignment between patches and class pentachora.
+        
+        Args:
+            patches: [B, N, D] - patch embeddings
+            pentachora: [C, 5, vocab_dim] - class pentachora
+        
+        Returns:
+            [B, N, C] - alignment scores
+        """
+        B, N, D = patches.shape
+        C = pentachora.shape[0]
+        
+        patches = self.norm(patches)
+        
+        # Compute alignment with each vertex
+        alignments = []
+        for v in range(5):
+            # Project patches through vertex-specific projection
+            patches_proj = self.vertex_projections[v](patches)
+            patches_proj = F.normalize(patches_proj, dim=-1)
+            
+            # Get vertex v of all classes
+            vertex_v = F.normalize(pentachora[:, v, :], dim=-1)
+            
+            # Compute alignment scores
+            alignment = torch.matmul(patches_proj, vertex_v.T)
+            alignments.append(alignment)
+        
+        # Average alignments across vertices
+        alignments = torch.stack(alignments, dim=-1).mean(dim=-1)
+        
+        return self.dropout(alignments)
+
+# ============================================
+# MLP BLOCK
+# ============================================
+
+class MLP(nn.Module):
+    """MLP block with GELU activation."""
+    def __init__(self, in_features: int, hidden_features: Optional[int] = None,
+                 out_features: Optional[int] = None, dropout: float = 0.):
+        super().__init__()
+        out_features = out_features or in_features
+        hidden_features = hidden_features or in_features
+        
+        self.fc1 = nn.Linear(in_features, hidden_features)
+        self.act = nn.GELU()
+        self.drop1 = nn.Dropout(dropout)
+        self.fc2 = nn.Linear(hidden_features, out_features)
+        self.drop2 = nn.Dropout(dropout)
+        
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        x = self.fc1(x)
+        x = self.act(x)
+        x = self.drop1(x)
+        x = self.fc2(x)
+        x = self.drop2(x)
+        return x
+
+# ============================================
+# VIT BLOCK WITH GEOMETRIC ATTENTION
+# ============================================
+
+class PentachoronViTBlock(nn.Module):
+    """ViT block with geometric attention for structured layers."""
+    def __init__(self, dim: int, heads: int = 8, mlp_ratio: float = 4.0,
+                 use_mesh: bool = True, dropout: float = 0., attn_dropout: float = 0.,
+                 drop_path: float = 0.):
+        super().__init__()
+        self.norm1 = nn.LayerNorm(dim)
+        
+        # Use GeometricAttention for structured layers, standard for others
+        if use_mesh:
+            self.attn = GeometricAttention(
+                dim=dim,
+                num_heads=heads,
+                num_regions=min(dim // heads, 16),
+                config=GeometricConfig(),
+                dropout=attn_dropout
+            )
+        else:
+            # Standard multi-head attention for later layers
+            self.attn = nn.MultiheadAttention(dim, heads, dropout=attn_dropout, batch_first=True)
+        
+        self.use_mesh = use_mesh
+        self.drop_path1 = DropPath(drop_path) if drop_path > 0. else nn.Identity()
+        
+        self.norm2 = nn.LayerNorm(dim)
+        mlp_hidden = int(dim * mlp_ratio)
+        self.mlp = MLP(in_features=dim, hidden_features=mlp_hidden, dropout=dropout)
+        self.drop_path2 = DropPath(drop_path) if drop_path > 0. else nn.Identity()
+        
+    def forward(self, x: torch.Tensor, preserve_structure: bool = True) -> torch.Tensor:
+        if self.use_mesh:
+            # GeometricAttention
+            attn_out, _ = self.attn(self.norm1(x))
+            x = x + self.drop_path1(attn_out)
+        else:
+            # Standard attention
+            normalized = self.norm1(x)
+            attn_out, _ = self.attn(normalized, normalized, normalized)
+            x = x + self.drop_path1(attn_out)
+        
+        x = x + self.drop_path2(self.mlp(self.norm2(x)))
+        return x
+
+# ============================================
+# PATCH EMBEDDING
+# ============================================
+
+class PatchEmbed(nn.Module):
+    """2D Image to Patch Embedding."""
+    def __init__(self, img_size: int = 32, patch_size: int = 4,
+                 in_chans: int = 3, embed_dim: int = 512):
+        super().__init__()
+        self.img_size = img_size
+        self.patch_size = patch_size
+        self.num_patches = (img_size // patch_size) ** 2
+        
+        self.proj = nn.Conv2d(in_chans, embed_dim, kernel_size=patch_size, stride=patch_size)
+        self.norm = nn.LayerNorm(embed_dim)
+        
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        x = self.proj(x)
+        x = rearrange(x, 'b c h w -> b (h w) c')
+        x = self.norm(x)
+        return x
+
+# ============================================
+# PENTACHORA VISION TRANSFORMER
+# ============================================
+
+class PentachoraViT(nn.Module):
+    """
+    Vision Transformer with pentachoron-based hierarchical CLS tokens
+    and geometric vocabulary integration.
+    """
+    def __init__(self, config: Optional[PentachoraConfig] = None, **kwargs):
+        super().__init__()
+        
+        # Use config or kwargs
+        if config is not None:
+            cfg = config
+        else:
+            cfg = PentachoraConfig(**kwargs)
+        
+        self.config = cfg
+        self.num_classes = cfg.num_classes
+        self.dim = cfg.dim
+        self.depth = cfg.depth
+        self.preserve_structure_until_layer = cfg.preserve_structure_until_layer
+        
+        # Set vocabulary dimension - from config, kwargs, or default to model dim
+        if cfg.vocab_dim is not None:
+            self.vocab_dim = cfg.vocab_dim
+        elif 'vocab_dim' in kwargs:
+            self.vocab_dim = kwargs['vocab_dim']
+        else:
+            self.vocab_dim = cfg.dim
+        
+        # Patch embedding
+        self.patch_embed = PatchEmbed(
+            cfg.img_size, cfg.patch_size, 3, cfg.dim
+        )
+        num_patches = self.patch_embed.num_patches
+        
+        # Positional embedding
+        self.pos_embed = nn.Parameter(torch.randn(1, num_patches, cfg.dim) * 0.02)
+        self.pos_drop = nn.Dropout(cfg.dropout_rate)
+        
+        # CLS tokens with pentachoron structure
+        self.cls_tokens = HierarchicalPentachoronCLS(cfg.dim, self.vocab_dim, cfg.num_classes)
+        
+        # Geometric projection layer - CREATE BEFORE vocab init
+        self.geometric_proj = GeometricProjection(cfg.dim, self.vocab_dim, cfg.num_classes, cfg.dropout_rate)
+        
+        # Initialize from vocabulary AFTER creating all components
+        if cfg.vocab is not None:
+            self._init_from_vocab(cfg.vocab)
+        
+        # Stochastic depth decay rule
+        dpr = [x.item() for x in torch.linspace(0, cfg.drop_path_rate, cfg.depth)]
+        
+        # Transformer blocks with geometric attention
+        self.blocks = nn.ModuleList([
+            PentachoronViTBlock(
+                dim=cfg.dim,
+                heads=cfg.heads,
+                mlp_ratio=cfg.mlp_ratio,
+                use_mesh=(cfg.use_mesh_attention and i < cfg.preserve_structure_until_layer),
+                dropout=cfg.dropout_rate,
+                attn_dropout=cfg.dropout_rate,
+                drop_path=dpr[i]
+            )
+            for i in range(cfg.depth)
+        ])
+        
+        # Final norm
+        self.norm = nn.LayerNorm(cfg.dim)
+        
+        # Classification heads
+        self.head = nn.Linear(cfg.dim, cfg.num_classes)
+        self.head_aux = nn.Linear(cfg.dim * 5, cfg.num_classes)
+        
+        # Initialize weights
+        self.apply(self._init_weights)
+        
+    def _init_weights(self, m: nn.Module):
+        """Initialize model weights."""
+        if isinstance(m, nn.Linear):
+            nn.init.trunc_normal_(m.weight, std=0.02)
+            if m.bias is not None:
+                nn.init.constant_(m.bias, 0)
+        elif isinstance(m, nn.LayerNorm):
+            nn.init.constant_(m.bias, 0)
+            nn.init.constant_(m.weight, 1.0)
+        elif isinstance(m, nn.Conv2d):
+            nn.init.kaiming_normal_(m.weight, mode='fan_out', nonlinearity='relu')
+            if m.bias is not None:
+                nn.init.constant_(m.bias, 0)
+    
+    def _init_from_vocab(self, vocab):
+        """Initialize class pentachora from geometric vocabulary."""
+        try:
+            print("Initializing pentachora from vocabulary...")
+            
+            if not hasattr(vocab, 'encode_batch'):
+                print("Vocabulary provided but encode_batch method not found, using random initialization")
+                return
+                
+            # Get CIFAR-100 class names
+            class_names = self._get_cifar100_classes()
+            
+            # Generate pentachora for all classes
+            pentachora_list = vocab.encode_batch(class_names[:self.num_classes], generate=True)
+            pentachora = np.stack(pentachora_list, axis=0)
+            
+            # Get actual dimensions from the encoded data
+            actual_vocab_dim = pentachora.shape[-1]
+            
+            print(f"Encoded pentachora shape: {pentachora.shape}")
+            print(f"Detected vocabulary dimension: {actual_vocab_dim}")
+            
+            # Validate basic shape requirements
+            if pentachora.shape[0] != self.num_classes or pentachora.shape[1] != 5:
+                print(f"Invalid shape: expected ({self.num_classes}, 5, ?), got {pentachora.shape}")
+                print("Using random initialization")
+                return
+            
+            # Update all components to use the actual vocabulary dimension
+            self.vocab_dim = actual_vocab_dim
+            self.cls_tokens.vocab_dim = actual_vocab_dim
+            self.geometric_proj.vocab_dim = actual_vocab_dim
+            
+            # Replace class_pentachora with the loaded vocabulary
+            self.cls_tokens.class_pentachora = nn.Parameter(
+                torch.tensor(pentachora, dtype=torch.float32)
+            )
+            
+            # Update/create projection layer if dimensions differ
+            if actual_vocab_dim != self.dim:
+                self.cls_tokens.vocab_projection = nn.Linear(actual_vocab_dim, self.dim)
+            else:
+                self.cls_tokens.vocab_projection = nn.Identity()
+            
+            # Rebuild geometric projection layers with correct dimensions
+            self.geometric_proj.vertex_projections = nn.ModuleList([
+                nn.Linear(self.dim, actual_vocab_dim, bias=False) for _ in range(5)
+            ])
+            
+            # Re-initialize the new layers
+            for proj in self.geometric_proj.vertex_projections:
+                nn.init.xavier_uniform_(proj.weight)
+            if actual_vocab_dim != self.dim:
+                nn.init.xavier_uniform_(self.cls_tokens.vocab_projection.weight)
+            
+            print(f"✓ Successfully initialized {self.num_classes} class pentachora from vocabulary")
+            print(f"  Vocabulary dimension: {actual_vocab_dim}")
+            print(f"  Model internal dimension: {self.dim}")
+            print(f"  Projection: {actual_vocab_dim} → {self.dim}")
+                
+        except Exception as e:
+            print(f"Error initializing from vocabulary: {e}")
+            print("Using random initialization")
+    
+    def _get_cifar100_classes(self):
+        """Get CIFAR-100 class names."""
+        return [
+            'apple', 'aquarium_fish', 'baby', 'bear', 'beaver', 'bed', 'bee', 'beetle', 
+            'bicycle', 'bottle', 'bowl', 'boy', 'bridge', 'bus', 'butterfly', 'camel', 
+            'can', 'castle', 'caterpillar', 'cattle', 'chair', 'chimpanzee', 'clock', 
+            'cloud', 'cockroach', 'couch', 'crab', 'crocodile', 'cup', 'dinosaur', 
+            'dolphin', 'elephant', 'flatfish', 'forest', 'fox', 'girl', 'hamster', 
+            'house', 'kangaroo', 'keyboard', 'lamp', 'lawn_mower', 'leopard', 'lion',
+            'lizard', 'lobster', 'man', 'maple_tree', 'motorcycle', 'mountain', 'mouse',
+            'mushroom', 'oak_tree', 'orange', 'orchid', 'otter', 'palm_tree', 'pear',
+            'pickup_truck', 'pine_tree', 'plain', 'plate', 'poppy', 'porcupine',
+            'possum', 'rabbit', 'raccoon', 'ray', 'road', 'rocket', 'rose',
+            'sea', 'seal', 'shark', 'shrew', 'skunk', 'skyscraper', 'snail', 'snake',
+            'spider', 'squirrel', 'streetcar', 'sunflower', 'sweet_pepper', 'table',
+            'tank', 'telephone', 'television', 'tiger', 'tractor', 'train', 'trout',
+            'tulip', 'turtle', 'wardrobe', 'whale', 'willow_tree', 'wolf', 'woman', 'worm'
+        ]
+    
+    def forward_features(self, x: torch.Tensor) -> Dict[str, torch.Tensor]:
+        """Extract features from input."""
+        B = x.shape[0]
+        
+        # Patch embedding
+        x = self.patch_embed(x)
+        x = x + self.pos_embed
+        x = self.pos_drop(x)
+        
+        # Get hierarchical CLS tokens
+        global_cls, vertex_cls = self.cls_tokens(B)
+        
+        # Concatenate CLS tokens with patches
+        x = torch.cat([global_cls, vertex_cls, x], dim=1)
+        
+        # Apply transformer blocks
+        for i, block in enumerate(self.blocks):
+            preserve = i < self.preserve_structure_until_layer
+            x = block(x, preserve_structure=preserve)
+        
+        # Apply final norm
+        x = self.norm(x)
+        
+        # Split tokens
+        global_cls = x[:, 0]
+        vertex_cls = x[:, 1:6]
+        patches = x[:, 6:]
+        
+        return {
+            'global_cls': global_cls,
+            'vertex_cls': vertex_cls,
+            'patches': patches
+        }
+    
+    def forward(self, x: torch.Tensor) -> Dict[str, torch.Tensor]:
+        """Forward pass through the model."""
+        features = self.forward_features(x)
+        
+        # Primary classification using global CLS
+        logits = self.head(features['global_cls'])
+        
+        # Auxiliary classification using vertex tokens
+        B = features['vertex_cls'].shape[0]
+        vertex_flat = features['vertex_cls'].reshape(B, -1)
+        aux_logits = self.head_aux(vertex_flat)
+        
+        # Geometric alignment scores
+        geometric_alignments = self.geometric_proj(
+            features['patches'], 
+            self.cls_tokens.class_pentachora
+        )
+        
+        return {
+            'logits': logits,
+            'aux_logits': aux_logits,
+            'geometric_alignments': geometric_alignments,
+            'vertex_cls': features['vertex_cls'],
+            'global_cls': features['global_cls'],
+            'patches': features['patches']
+        }
+
+# ============================================
+# LOSS FUNCTIONS
+# ============================================
+
+class PentachoraLoss(nn.Module):
+    """Combined loss for PentachoraViT training."""
+    def __init__(self, aux_weight: float = 0.3, geo_weight: float = 0.1,
+                 smoothing: float = 0.0):
+        super().__init__()
+        self.aux_weight = aux_weight
+        self.geo_weight = geo_weight
+        self.criterion = nn.CrossEntropyLoss(label_smoothing=smoothing)
+        
+    def forward(self, outputs: Dict[str, torch.Tensor], targets: torch.Tensor) -> torch.Tensor:
+        """Compute combined loss."""
+        # Primary classification loss
+        loss = self.criterion(outputs['logits'], targets)
+        
+        # Auxiliary loss from vertex tokens
+        if 'aux_logits' in outputs and self.aux_weight > 0:
+            aux_loss = self.criterion(outputs['aux_logits'], targets)
+            loss = loss + self.aux_weight * aux_loss
+        
+        # Geometric alignment loss
+        if 'geometric_alignments' in outputs and self.geo_weight > 0:
+            # Average over patches
+            geo_logits = outputs['geometric_alignments'].mean(dim=1)
+            geo_loss = self.criterion(geo_logits, targets)
+            loss = loss + self.geo_weight * geo_loss
+        
+        return loss
+
+# ============================================
+# MODEL REGISTRY AND BUILDERS
+# ============================================
+
+MODEL_CONFIGS = {
+    'pentachora_spark': PentachoraConfig(
+        dim=64, depth=5, heads=4, mlp_ratio=4.0,
+        preserve_structure_until_layer=2,
+        dropout_rate=0.0, drop_path_rate=0.0
+    ),
+    'pentachora_tiny': PentachoraConfig(
+        dim=384, depth=12, heads=6, mlp_ratio=4.0,
+        preserve_structure_until_layer=6,
+        dropout_rate=0.1, drop_path_rate=0.1
+    ),
+    'pentachora_small': PentachoraConfig(
+        dim=512, depth=12, heads=8, mlp_ratio=4.0,
+        preserve_structure_until_layer=6,
+        dropout_rate=0.1, drop_path_rate=0.1
+    ),
+    'pentachora_base': PentachoraConfig(
+        dim=768, depth=12, heads=12, mlp_ratio=4.0,
+        preserve_structure_until_layer=8,
+        dropout_rate=0.1, drop_path_rate=0.2
+    ),
+    'pentachora_large': PentachoraConfig(
+        dim=1024, depth=24, heads=16, mlp_ratio=4.0,
+        preserve_structure_until_layer=12,
+        dropout_rate=0.1, drop_path_rate=0.3
+    ),
+}
+
+def create_pentachora_vit(variant: str = 'pentachora_small',
+                         pretrained: bool = False,
+                         **kwargs) -> PentachoraViT:
+    """
+    Create PentachoraViT model.
+    
+    Args:
+        variant: Model variant name
+        pretrained: Whether to load pretrained weights
+        **kwargs: Override config parameters (including vocab_dim)
+    
+    Returns:
+        PentachoraViT model
+    """
+    if variant not in MODEL_CONFIGS:
+        raise ValueError(f"Unknown variant: {variant}. Choose from {list(MODEL_CONFIGS.keys())}")
+    
+    config = MODEL_CONFIGS[variant]
+    
+    # Override config with kwargs
+    for key, value in kwargs.items():
+        setattr(config, key, value)
+    
+    model = PentachoraViT(config)
+    
+    if pretrained:
+        warnings.warn("Pretrained weights not available yet")
+    
+    return model
+
+def pentachora_vit_spark(pretrained: bool = False, **kwargs) -> PentachoraViT:
+    """Create spark variant (smallest)."""
+    return create_pentachora_vit('pentachora_spark', pretrained=pretrained, **kwargs)
+
+def pentachora_vit_tiny(pretrained: bool = False, **kwargs) -> PentachoraViT:
+    """Create tiny variant."""
+    return create_pentachora_vit('pentachora_tiny', pretrained=pretrained, **kwargs)
+
+def pentachora_vit_small(pretrained: bool = False, **kwargs) -> PentachoraViT:
+    """Create small variant."""
+    return create_pentachora_vit('pentachora_small', pretrained=pretrained, **kwargs)
+
+def pentachora_vit_base(pretrained: bool = False, **kwargs) -> PentachoraViT:
+    """Create base variant."""
+    return create_pentachora_vit('pentachora_base', pretrained=pretrained, **kwargs)
+
+def pentachora_vit_large(pretrained: bool = False, **kwargs) -> PentachoraViT:
+    """Create large variant."""
+    return create_pentachora_vit('pentachora_large', pretrained=pretrained, **kwargs)
+
+# ============================================
+# TRAINING UTILITIES
+# ============================================
+
+def get_parameter_groups(model: PentachoraViT, 
+                        weight_decay: float = 0.05) -> List[Dict[str, Any]]:
+    """
+    Get parameter groups for optimizer with weight decay handling.
+    
+    Args:
+        model: PentachoraViT model
+        weight_decay: Weight decay value
+    
+    Returns:
+        List of parameter group dictionaries
+    """
+    no_decay = ['bias', 'norm', 'LayerNorm']
+    
+    decay_params = []
+    no_decay_params = []
+    
+    for name, param in model.named_parameters():
+        if not param.requires_grad:
+            continue
+        
+        if any(nd in name for nd in no_decay):
+            no_decay_params.append(param)
+        else:
+            decay_params.append(param)
+    
+    return [
+        {'params': decay_params, 'weight_decay': weight_decay},
+        {'params': no_decay_params, 'weight_decay': 0.0}
+    ]
+
+def count_parameters(model: nn.Module) -> Dict[str, int]:
+    """Count model parameters."""
+    total = sum(p.numel() for p in model.parameters())
+    trainable = sum(p.numel() for p in model.parameters() if p.requires_grad)
+    return {
+        'total': total,
+        'trainable': trainable,
+        'non_trainable': total - trainable
+    }
+
+# ============================================
+# INFERENCE UTILITIES
+# ============================================
+
+@torch.no_grad()
+def extract_features(model: PentachoraViT, 
+                     images: torch.Tensor,
+                     feature_type: str = 'global_cls') -> torch.Tensor:
+    """
+    Extract features from images using the model.
+    
+    Args:
+        model: PentachoraViT model
+        images: Input images [B, 3, H, W]
+        feature_type: Type of features to extract
+            - 'global_cls': Global CLS token
+            - 'vertex_cls': Vertex CLS tokens
+            - 'patches': Patch embeddings
+    
+    Returns:
+        Extracted features
+    """
+    model.eval()
+    features = model.forward_features(images)
+    return features.get(feature_type, features['global_cls'])
+
+# ============================================
+# EXAMPLE USAGE AND TESTING
+# ============================================
+
+def test_model():
+    """Test model creation and forward pass."""
+    print("Testing PentachoraViT Model with Geometric Attention")
+    print("=" * 50)
+    
+    # Test different variants
+    variants = ['pentachora_spark', 'pentachora_tiny', 'pentachora_small']
+    
+    for variant in variants:
+        print(f"\nTesting {variant}:")
+        
+        # Create model with vocab_dim
+        model = create_pentachora_vit(
+            variant=variant,
+            img_size=32,
+            patch_size=4,
+            num_classes=100,
+            vocab_dim=64  # Test with 64-dim vocabulary
+        )
+        
+        # Count parameters
+        params = count_parameters(model)
+        print(f"  Total parameters: {params['total']:,}")
+        print(f"  Trainable parameters: {params['trainable']:,}")
+        
+        # Test forward pass
+        x = torch.randn(2, 3, 32, 32)
+        outputs = model(x)
+        
+        print(f"  Output shapes:")
+        print(f"    Logits: {outputs['logits'].shape}")
+        print(f"    Aux logits: {outputs['aux_logits'].shape}")
+        print(f"    Geometric alignments: {outputs['geometric_alignments'].shape}")
+        
+        # Test loss computation
+        loss_fn = PentachoraLoss()
+        targets = torch.randint(0, 100, (2,))
+        loss = loss_fn(outputs, targets)
+        print(f"  Loss: {loss.item():.4f}")
+        
+        # Test feature extraction
+        features = extract_features(model, x, 'global_cls')
+        print(f"  Extracted features shape: {features.shape}")
+    
+    print("\n" + "=" * 50)
+    print("All tests passed!")
+
+if __name__ == "__main__":
+    # Run tests
+    test_model()
+    
+    # Example: Create model for training with vocabulary
+    print("\nExample: Creating model for training with 64-dim vocabulary")
+    model = pentachora_vit_spark(
+        img_size=32,
+        patch_size=4,
+        num_classes=100,
+        vocab_dim=64,  # Specify vocabulary dimension
+        dropout_rate=0.0,
+        drop_path_rate=0.0
+    )
+    
+    # Get parameter groups for optimizer
+    param_groups = get_parameter_groups(model, weight_decay=0.05)
+    print(f"Number of parameter groups: {len(param_groups)}")
+    
+    # Example batch
+    images = torch.randn(4, 3, 32, 32)
+    targets = torch.randint(0, 100, (4,))
+    
+    # Forward pass
+    outputs = model(images)
+    
+    # Compute loss
+    criterion = PentachoraLoss(aux_weight=0.3, geo_weight=0.1)
+    loss = criterion(outputs, targets)
+    
+    print(f"Training loss: {loss.item():.4f}")
+    print("\nModel ready for training with geometric attention!")