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Orthogonal splitting of positive semidefinite matrices: the theorem

GaussianApplications.PsdSplittingTheoremapplications/PsdSplittingTheorem.v28 lines1 lemma and theoremsource
Imports 4 library modules and 7 external

External: HB.structures, mathcomp.classical.all_ssreflect_compat, mathcomp.algebra.algebraic_hierarchy.ssralg, mathcomp.algebra.numeric_hierarchy.ssrnum, mathcomp.algebra.matrix, mathcomp.algebra.sesquilinear, mathcomp.reals.reals

Target T5 of phase 12 (AGENTS.md, section Phase 12). psd_splitting_theorem proves psd_splitting_statement of PsdSplittingStatement.v, the lemma 'Orthogonal splitting' of 'Exponential PSD rank of positively shifted matching matrices' (family 126 of the OpenAI math collection, revision 1581d4cbd, source/sections/splitting.tex), from psd_splitting of library/matrix/psd_splitting.v, a Rocq formalization of the credited argument. The statement indexes L >= 1 matrices by 'I_L; the library lemma takes L + 1 matrices, with constant 2^L.

Main results

ResultsStatement
Proves psd_splitting_statement (T5): for every R : realType, L >= 1 and positive semidefinite A_1, ..., A_L of 'M[R]_n, there are orthogonal projections P_1, ..., P_L, possibly zero, with P_s P_t = 0 for s != t and sum_s P_s = 1, and sum_z sum_(s != z) |P_s A_z P_s|_F^2 <= 2^(L-1) sum_z sum_(z' != z) tr (A_z A_z'), from psd_splitting of library/matrix/psd_splitting.v.

Declarations1 exported

lemma, theoremdefinitioninstancelocal
Main result, as the README states it

Proves psd_splitting_statement (T5): for every R : realType, L >= 1 and positive semidefinite A_1, ..., A_L of 'M[R]_n, there are orthogonal projections P_1, ..., P_L, possibly zero, with P_s P_t = 0 for s != t and sum_s P_s = 1, and sum_z sum_(s != z) |P_s A_z P_s|_F^2 <= 2^(L-1) sum_z sum_(z' != z) tr (A_z A_z'), from psd_splitting of library/matrix/psd_splitting.v.

Statement as written in the source
Theorem psd_splitting_theorem : psd_splitting_statement.
Generated from commit 9046883 (tag phase12) of the ellipsoid fitting repository. Signatures are printed by Rocq 9.1.1; links in the source statements come from the compiled .glob files. The source links open the files on GitHub at this commit, in the now-public repository.