CyberdyneLabs · Reports · PHYSARIUM_COVERAGE_AUDIT

PHYSARIUM_COVERAGE_AUDIT

reports/PHYSARIUM_COVERAGE_AUDIT.md 545 words raw markdown ↗

PHYSARIUM_COVERAGE_AUDIT

Date: 2026-04-27 Why: Earlier PHYSARIUM_RESULTS_RECONCILE.md (first draft) speculated that Physarium-v1 surgery covered ≈ 6 % of target weights via 256×256 windows. That was wrong. This audit reconstructs the actual coverage from the surgery code (src/physarium/physarium_engine.cpp) and the per-tensor log (reports/physarium7b_surgery_run.log).

How surgery actually iterates the matrix

prune_matrix() walks non-overlapping block_size × block_size tiles (default block_size = 256), with min(...) clipping at the matrix edges:

for (int bi = 0; bi < rows; bi += p.block_size) {
    for (int bj = 0; bj < cols; bj += p.block_size) {
        int br = std::min(p.block_size, rows - bi);
        int bc = std::min(p.block_size, cols - bj);
        // process tile [bi..bi+br, bj..bj+bc]
    }
}

This means every weight in every target tensor is processed exactly once. Coverage of the target tensor set is 100 %.

Audit numbers (Physarium-7B)

Reconstructed from the safetensors index + the per-tensor surgery log.

| Quantity | Elements | Pct of target | Pct of full | |----------------------------------------------|------------------|---------------|-------------| | Total elements in full 7B model | 7,615,616,512 | — | 100 % | | Target proj elements (q/k/v/o + gate/up/down)| 6,525,288,448 | 100 % | 85.68 % | | Processed (logged) by surgery | 6,525,288,448 | 100.00 % | 85.68 % | | Killed (zeroed) by surgery | 1,450,103,613 | 22.22 % | 19.04 % | | Tensors processed | 196 (28×7) | — | — |

processed / total_target = 100.00 % — surgery did not skip a tile.

Per-projection sparsity (audit)

| Projection | Processed elements | Killed elements | Killed % | |-----------------------|--------------------|-----------------|----------| | mlp.down_proj | 1,901,068,288 | 426,068,415 | 22.41 % | | mlp.gate_proj | 1,901,068,288 | 421,099,975 | 22.15 % | | mlp.up_proj | 1,901,068,288 | 419,952,080 | 22.09 % | | self_attn.k_proj | 51,380,224 | 11,914,046 | 23.19 % | | self_attn.o_proj | 359,661,568 | 78,357,784 | 21.79 % | | self_attn.q_proj | 359,661,568 | 81,377,034 | 22.63 % | | self_attn.v_proj | 51,380,224 | 11,334,279 | 22.06 % |

What this means for prior claims

| Claim source | Original phrasing | Audit verdict | |-------------------------------------------|-----------------------------------------|---------------| | PHYSARIUM7B_SURGERY_REPORT.md | "1,450,103,613 / 6,525,288,448 = 22.22 % of target proj weights" | ✅ correct as stated | | GIGACHAD_PHASE7_CONSOLIDATED.md | "22.22 % of target proj weights" | ✅ correct as stated | | PHYSARIUM_RESULTS_RECONCILE.md (first draft) | "practical surgery coverage is ≈ 6 %" | ❌ wrong, replaced |

Correct statements going forward

6,525,288,448), not over a sampled 6 % window.

7,615,616,512). Use this when comparing against "model-wide sparsity" numbers from other pruning literature.

biases) — together ~14.32 % of model — were untouched (BF16 copied verbatim).

|w|, not activation contribution). That separate critique stands; it is about what the surgery sees, not how much of the matrix it sees.

Raw machine-readable copy

reports/physarium_coverage_audit.json — full JSON with per-projection counts, ratios, and the denominator_correct: true reconcile flag.

Source of truth references