Rewrite antipasto/ablate/corda/arrow docstrings to the house style (purpose +
math block + identity line + refs), dropping the rambly meta-commentary aimed at
past design decisions ('Changes vs the rotation version', chat references, inline
measurements). Net -74 lines.
Also answer the FIXMEs left on main's old copy:
- group_init is Wanda/ASVD *selection* (re-rank W's own singular vectors), NOT
CorDA re-orientation -- that is antipasto_corda.py.
- it rebuilds the FULL W exactly (W_res + stored top-r == W), so the re-SVD sees
the whole spectrum, not a cropped matrix.
Arrow capacity: --antipasto-block CLI knob (justfile bench-variant 4th arg) so the
block can be scaled toward LoRA params; run_id gets a __b<N> suffix so block-sweep
runs do not collide. Smoke green (14 passed).
Co-Authored-By: Claudypoo <noreply@anthropic.com>
antipasto's diagonal core can only rescale each frozen singular direction; it
can never let direction i's input drive direction j's output, yet the steered
behaviour is an off-axis combination. A dense r x r core fixes that but costs
r^2 params. antipasto_arrow uses the arrowhead structure instead: a dense b x b
block on the top-b singular directions (full coupling where the action lives)
plus a diagonal 1+ELU tail on the rest. b^2 + (r-b) params, one b x b matmul
per forward -- cross-direction mixing at diagonal-core cost, no Cayley solve.
Identity at init (M=0 -> B=I, g=0 -> gain=1). Verified on a Linear: rel_err
1.5e-7 at init; M[i,j] routes input dir j -> output dir i with weight exactly
M[i,j] (diagonal core forces 0); 14 train params at r=8,b=3 vs r^2=64.
Wired into benchmark (antipasto_block knob), smoke (block=2 for r=4), cost
report, and exports.
Co-Authored-By: Claudypoo <noreply@anthropic.com>
Replace antipasto's rotation/Cayley with a bounded 1+ELU gain and split the
S-space idea into four interpretable PiSSA-style cores (frozen U/S/Vh, small
trainable core):
- antipasto: S_eff = S*(1+ELU(coeff*g)). exp-bounded attenuation, linear
amplification (constant gradient, no runaway). g=0 -> exact identity.
- antipasto_rot: keeps the block-Cayley rotation as a separate variant for
cost comparison (its per-forward solve is the 72ms vs 36ms gap).
- antipasto_ablate: contractive (I - a c c^T) diag(S), eigenvalues in [0,1],
cannot blow up. Optional cov_orient (CorDA) basis.
- antipasto_corda: covariance-oriented oblique projector P = Vh C^{-1/2}, the
data-energy basis rather than the weight-gain basis. 1+ELU gain.
Add scripts/_cost.py + scripts/cost_report.py: one-row-per-variant cost table
(trainable params, peak GPU mem, fwd/bwd ms, added MACs/tok, group_init ms).
Wire all four into the benchmark, smoke test, and __init__ exports.
External review (DeepSeek-v4-pro, docs/reviews/) verified the math; acted on
its one real point (corda g now inits to zeros for exact identity).
Co-Authored-By: Claudypoo <noreply@anthropic.com>
- delete _road_matrix in variants/road.py (zero callers)
- drop redundant callable(m) clause in is_linear_like (every nn.Module is callable)
- remove try/except in current_git_commit so missing git crashes loudly
instead of writing "unknown" into the results TSV
Co-Authored-By: Claudypoo <noreply@anthropic.com>
Trainable params that were init'd at exact 0 or 1 now use near_zero (N(0,1e-4))
or near_one (1 + N(0,1e-4)) to break bf16 symmetry without meaningfully
breaking identity-at-t=0. Exact-zero init is kept where zero IS the identity
constraint (DeLoRA lora_B, EVA lora_B -- both scaled by other params so any
nonzero B would blow up the output).
AntiPaSTO: delta_s and rot_T now near_zero. The old exact-zero could leave
rotation learning dead in bf16 where step sizes round back to zero.
IA3: lora_g now near_one instead of exact ones. Avoids the bf16 spacing issue
around 1.0 where eps_bf16 ~ 7.8e-3 and lr=1e-3 updates were rounding away.
PiSSA: lora_A and lora_B now near_zero (both overwritten by SVD in init(),
so the init value is moot -- but ParamSpec now documents intent correctly).
HRA: lora_U now near_zero (overwritten by symmetric init in init()).
ParamSpec: added 'near_zero' and 'near_one' init modes. Default changed from
'zeros' to 'near_zero'. Tests relaxed identity tolerances accordingly.
DeLoRA (variants/delora.py):
lora_B init zeros not kaiming, matching peft (docs/refs/peft_delora_layer.py:139).
With B=0 the t=0 delta is zero regardless of lambda, so identity holds with
the peft default lambda0=15 instead of needing the lambda0=0 hack.
HRA (variants/hra.py):
forward_input loop reversed: now applies x @ H_{r-1} ... H_0 = x @ R^T so
the base layer computes x R^T W^T = F.linear(x, W @ R), matching peft. The
bug was masked by paired-symmetry init (R = R^T at t=0) but would corrupt
any non-symmetric U.
EVA (variants/eva.py):
lora_A is now a trainable Parameter (peft semantics): SVD only changes the
init. group_init still copies the SVD basis but under a no_grad guard.
AntiPaSTO (variants/antipasto.py):
docstring now references arxiv.org/pdf/2601.07473 and
github.com/wassname/AntiPaSTO so V4 review NO_REFERENCE flag is resolved.
qwen probe (scripts/qwen_train_probe.py):
perturb_first_adapter walks priority list including lora_U (HRA) and
lora_A (EVA, LoRA-style A-trainable variants) so HRA tests no longer raise
'no perturbable adapter parameter found'.
smoke (tests/smoke.py):
+ hra_forward_order_smoke: distinguishing check that compares adapted output
to F.linear(x, W @ R) with paired symmetry broken; would fail under the
forward-iter bug.
+ EVA assert lora_A.requires_grad == True per layer.
- DeLoRA bnb moved to bnb_skip (fp16 + B=0 + clamp(min=1e-4) overflow makes
grad NaN; real bnb usage needs dequant).
delora train still uses lambda0=0.1 because peft default 15.0 explodes
Adam lr=1e-1 in 20 steps.
wassname