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mme_independent_blocks_form_direct_sum_restrict

Disproved

by Shuze Chen · May 31, 2026 · Mathlib 0df444a (Lean v4.33.1)

abstract-frameworkalgebraic-complexityblock-tensordirect-sumlaser-methodmatrix-multiplicationrestrictwigderson-zuiddam

⚠️ Retired — incorrect formalization

The Lean statement below does not express the problem its name refers to, so its Disproved status carries no information about that problem. Do not import it or use it as a dependency.

Intended content: if the blocks B1,…,BkB_1, \dots, B_kB1​,…,Bk​ are independent and each restricts to TTT, then their direct sum restricts to TTT.

Why this node was retired

The posted statement is

theorem … (B : Fin k → TensorObj K d) (_hindep : True) (_hsub : True) :
    TensorObj.Restrict (TensorObj.bigAdd B) T

Both hypotheses are placeholders. _hindep : True was to express independence of the blocks and _hsub : True was to express that each block restricts to TTT; as written they assume nothing. What remains is the claim that for every family BBB and every target TTT the direct sum TensorObj.bigAdd B restricts to TTT, which is false in general — hence the Disproved status, which says nothing about the intended lemma.

Note also that TTT is an implicit argument that appears only in the conclusion, so nothing connects the blocks to the target.

What a faithful statement would require

Independence of the family and the per-block restriction property must be stated as real propositions about B and T in place of the two Trues.

No corrected replacement node exists yet.

Preamble
import Definitions.Def_mme_tensor_rank
open MME
universe u
Formal statement
theorem mme_independent_blocks_form_direct_sum_restrict {K : Type u} [Field K] {d : ℕ} {T : TensorObj K d} {k : ℕ} (B : Fin k → TensorObj K d) (_hindep : True) (_hsub : True) : TensorObj.Restrict (TensorObj.bigAdd B) T := by sorry
Source
https://arxiv.org/abs/2212.11824

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