Hermes-agent

plugins/memory/holographic/holographic.py

@@ -0,0 +1,203 @@
+"""Holographic Reduced Representations (HRR) with phase encoding.
+
+HRRs are a vector symbolic architecture for encoding compositional structure
+into fixed-width distributed representations. This module uses *phase vectors*:
+each concept is a vector of angles in [0, 2π). The algebraic operations are:
+
+  bind   — circular convolution (phase addition)  — associates two concepts
+  unbind — circular correlation (phase subtraction) — retrieves a bound value
+  bundle — superposition (circular mean)           — merges multiple concepts
+
+Phase encoding is numerically stable, avoids the magnitude collapse of
+traditional complex-number HRRs, and maps cleanly to cosine similarity.
+
+Atoms are generated deterministically from SHA-256 so representations are
+identical across processes, machines, and language versions.
+
+References:
+  Plate (1995) — Holographic Reduced Representations
+  Gayler (2004) — Vector Symbolic Architectures answer Jackendoff's challenges
+"""
+
+import hashlib
+import logging
+import struct
+import math
+
+try:
+    import numpy as np
+    _HAS_NUMPY = True
+except ImportError:
+    _HAS_NUMPY = False
+
+logger = logging.getLogger(__name__)
+
+_TWO_PI = 2.0 * math.pi
+
+
+def _require_numpy() -> None:
+    if not _HAS_NUMPY:
+        raise RuntimeError("numpy is required for holographic operations")
+
+
+def encode_atom(word: str, dim: int = 1024) -> "np.ndarray":
+    """Deterministic phase vector via SHA-256 counter blocks.
+
+    Uses hashlib (not numpy RNG) for cross-platform reproducibility.
+
+    Algorithm:
+    - Generate enough SHA-256 blocks by hashing f"{word}:{i}" for i=0,1,2,...
+    - Concatenate digests, interpret as uint16 values via struct.unpack
+    - Scale to [0, 2π): phases = values * (2π / 65536)
+    - Truncate to dim elements
+    - Returns np.float64 array of shape (dim,)
+    """
+    _require_numpy()
+
+    # Each SHA-256 digest is 32 bytes = 16 uint16 values.
+    values_per_block = 16
+    blocks_needed = math.ceil(dim / values_per_block)
+
+    uint16_values: list[int] = []
+    for i in range(blocks_needed):
+        digest = hashlib.sha256(f"{word}:{i}".encode()).digest()
+        uint16_values.extend(struct.unpack("<16H", digest))
+
+    phases = np.array(uint16_values[:dim], dtype=np.float64) * (_TWO_PI / 65536.0)
+    return phases
+
+
+def bind(a: "np.ndarray", b: "np.ndarray") -> "np.ndarray":
+    """Circular convolution = element-wise phase addition.
+
+    Binding associates two concepts into a single composite vector.
+    The result is dissimilar to both inputs (quasi-orthogonal).
+    """
+    _require_numpy()
+    return (a + b) % _TWO_PI
+
+
+def unbind(memory: "np.ndarray", key: "np.ndarray") -> "np.ndarray":
+    """Circular correlation = element-wise phase subtraction.
+
+    Unbinding retrieves the value associated with a key from a memory vector.
+    unbind(bind(a, b), a) ≈ b  (up to superposition noise)
+    """
+    _require_numpy()
+    return (memory - key) % _TWO_PI
+
+
+def bundle(*vectors: "np.ndarray") -> "np.ndarray":
+    """Superposition via circular mean of complex exponentials.
+
+    Bundling merges multiple vectors into one that is similar to each input.
+    The result can hold O(sqrt(dim)) items before similarity degrades.
+    """
+    _require_numpy()
+    complex_sum = np.sum([np.exp(1j * v) for v in vectors], axis=0)
+    return np.angle(complex_sum) % _TWO_PI
+
+
+def similarity(a: "np.ndarray", b: "np.ndarray") -> float:
+    """Phase cosine similarity. Range [-1, 1].
+
+    Returns 1.0 for identical vectors, near 0.0 for random (unrelated) vectors,
+    and -1.0 for perfectly anti-correlated vectors.
+    """
+    _require_numpy()
+    return float(np.mean(np.cos(a - b)))
+
+
+def encode_text(text: str, dim: int = 1024) -> "np.ndarray":
+    """Bag-of-words: bundle of atom vectors for each token.
+
+    Tokenizes by lowercasing, splitting on whitespace, and stripping
+    leading/trailing punctuation from each token.
+
+    Returns bundle of all token atom vectors.
+    If text is empty or produces no tokens, returns encode_atom("__hrr_empty__", dim).
+    """
+    _require_numpy()
+
+    tokens = [
+        token.strip(".,!?;:\"'()[]{}")
+        for token in text.lower().split()
+    ]
+    tokens = [t for t in tokens if t]
+
+    if not tokens:
+        return encode_atom("__hrr_empty__", dim)
+
+    atom_vectors = [encode_atom(token, dim) for token in tokens]
+    return bundle(*atom_vectors)
+
+
+def encode_fact(content: str, entities: list[str], dim: int = 1024) -> "np.ndarray":
+    """Structured encoding: content bound to ROLE_CONTENT, each entity bound to ROLE_ENTITY, all bundled.
+
+    Role vectors are reserved atoms: "__hrr_role_content__", "__hrr_role_entity__"
+
+    Components:
+    1. bind(encode_text(content, dim), encode_atom("__hrr_role_content__", dim))
+    2. For each entity: bind(encode_atom(entity.lower(), dim), encode_atom("__hrr_role_entity__", dim))
+    3. bundle all components together
+
+    This enables algebraic extraction:
+        unbind(fact, bind(entity, ROLE_ENTITY)) ≈ content_vector
+    """
+    _require_numpy()
+
+    role_content = encode_atom("__hrr_role_content__", dim)
+    role_entity = encode_atom("__hrr_role_entity__", dim)
+
+    components: list[np.ndarray] = [
+        bind(encode_text(content, dim), role_content)
+    ]
+
+    for entity in entities:
+        components.append(bind(encode_atom(entity.lower(), dim), role_entity))
+
+    return bundle(*components)
+
+
+def phases_to_bytes(phases: "np.ndarray") -> bytes:
+    """Serialize phase vector to bytes. float64 tobytes — 8 KB at dim=1024."""
+    _require_numpy()
+    return phases.tobytes()
+
+
+def bytes_to_phases(data: bytes) -> "np.ndarray":
+    """Deserialize bytes back to phase vector. Inverse of phases_to_bytes.
+
+    The .copy() call is required because frombuffer returns a read-only view
+    backed by the bytes object; callers expect a mutable array.
+    """
+    _require_numpy()
+    return np.frombuffer(data, dtype=np.float64).copy()
+
+
+def snr_estimate(dim: int, n_items: int) -> float:
+    """Signal-to-noise ratio estimate for holographic storage.
+
+    SNR = sqrt(dim / n_items) when n_items > 0, else inf.
+
+    The SNR falls below 2.0 when n_items > dim / 4, meaning retrieval
+    errors become likely. Logs a warning when this threshold is crossed.
+    """
+    _require_numpy()
+
+    if n_items <= 0:
+        return float("inf")
+
+    snr = math.sqrt(dim / n_items)
+
+    if snr < 2.0:
+        logger.warning(
+            "HRR storage near capacity: SNR=%.2f (dim=%d, n_items=%d). "
+            "Retrieval accuracy may degrade. Consider increasing dim or reducing stored items.",
+            snr,
+            dim,
+            n_items,
+        )
+
+    return snr