Cube Memory

Research code investigating Vector Symbolic Architecture (VSA) memory layers as a replacement for transformer feed-forward (FFN) blocks. The idea: instead of looking up values by learned nearest-neighbor similarity, retrieve them by orientation — algebraic unbind against a structured FHRR codebook ("rotate to face θ, read the snapshot"). The goal was a matmul-free, bandwidth-cheap stand-in for the dense FFN that dominates per-token weight reads.

Status

Negative result — the core hypothesis does not work. This repo is the experimental record behind a paper titled "Two Negative Results for Vector Symbolic Architectures: FFN Replacement and Compositional Image Generation." The FFN-replacement direction (Case Study 1) fails because of a rank bottleneck: a VSA cleanup→bind→retrieve pipeline has effective rank bounded by top-k (typically ~4), while real FFN mappings are ~89% linear with effective rank >2048. A 164K-parameter rank-16 linear projection captures more variance than a 35M-parameter VSA memory layer, and scaling top-k does not close the gap. The companion direction (Rubik Gen — compositional image generation via token binding, rubik-gen/) fails for separate reasons documented in IDEAS_FUTURE_PAPER_2_RUBIK_GEN.md and folds in as Case Study 2.

The experiments are complete and the figures are generated; the work is kept here as a documented negative result and portfolio artifact rather than a usable library. Do not expect a shippable FFN replacement here.

What's in the repo

• SPEC.md, PAPER_OUTLINE.md, LOCAL_DISTILL_PLAN.md, RISKS.md — design, plan, and the bandwidth motivation.
• phase0/ — FHRR primitives (fhrr.py) and a recall sanity test.
• phase1/ — the bulk of the work: cube_memory_layer*.py (the VSA memory layer, v1–v3), SVD codebook extraction, FFN-swap harness, per-layer training, reviewer ablation experiments, and tests/.
• rubik-gen/ — the compositional image-generation experiments (Case Study 2) with results JSON and figures.
• shaders/ — Rust-GPU (rust-gpu → SPIR-V) compute kernels for the layer, with a CPU parity test. Intended for a Phase 2 Vulkan integration that was not reached.
• paper/ — LaTeX source, bibliography, figures, and a compiled main.pdf.
• reviewer_results/, *_STATUS.md, EVAL_RESULTS.md, V3_ANALYSIS.md — measured numbers, status logs, and analysis.

Most analysis numbers and design rationale live in the Markdown status files; start with PAPER_OUTLINE.md for the overall story and phase1/PLAN.md for the experiment plan.

Running the experiments

The experiments are Python scripts plus a Rust shader crate; there is no single entry point or packaged module. Each script is meant to be run on its own.

Python (phase0 / phase1 / rubik-gen)

python -m venv .venv && source .venv/bin/activate
pip install torch numpy   # plus transformers/datasets for the scripts that pull a model

Then run an individual script, e.g.:

python phase0/recall_test.py
python phase1/reviewer_exp1_svd_spectrum.py

Scripts that load a model (e.g. activation extraction, distillation) expect a local Qwen3 GGUF / HF checkpoint and a llama.cpp Vulkan build; paths are set inside the scripts and will need editing for your environment.

Rust shaders

cd shaders

# CPU reference unit tests — pure Rust, run on the stable toolchain,
# no GPU or prebuilt SPIR-V needed. These pin the FHRR/Cube-Memory
# reference algebra that the GPU parity tests compare against.
cargo test -p cube-memory-host --lib

# Full GPU/CPU parity tests — require a Vulkan adapter AND the shader
# binary built first via the rust-gpu nightly toolchain:
cargo run  -p cube-memory-shader-builder --release
cargo test -p cube-memory-host --release   # runs tests/parity.rs

See shaders/README.md for the rust-gpu toolchain details (the pinned nightly and components needed to build the SPIR-V).

Limitations

• This is research/experiment code, not a library — no stable API and no packaging. CI (.github/workflows/ci.yml) covers only the deterministic, hardware-free surface: the Rust host crate's CPU reference path (build + clippy + unit tests) and a Python syntax check / ruff lint. The rust-gpu shader build and the GPU parity tests are out of CI scope (nightly toolchain + Vulkan adapter required).
• Hardware-specific: numbers were measured on an AMD Radeon 890M (gfx1150) Vulkan build of llama.cpp; the bandwidth and t/s figures are local measurements, not general benchmarks.
• The headline conclusion is negative; the layer does not match a linear baseline.

License

MIT — see LICENSE.