A finite setting for invariant rediscovery [ftip-00NS]

✍️sourceAGENTDRAFTED

A first concrete family can use linear chain complexes over the two-element field \(\mathbb F_2\). This adapts the incidence-matrix concept-discovery setting of Aggarwal et al. into an exact finite experiment. The chosen field, transformations and certificate tasks below are part of this proposal, not a reproduction of that paper.

An object consists of vector spaces of dimensions \(n_0,n_1,n_2\) and matrices \(D_1:\mathbb F_2^{n_1}\to \mathbb F_2^{n_0}\) and \(D_2:\mathbb F_2^{n_2}\to \mathbb F_2^{n_1}\) satisfying \(D_1D_2=0\). All entries, dimensions and allowed operations are public. Arithmetic is exact. Zero-dimensional spaces and zero maps are included. The experiment can provide only matrices and arithmetic, or additionally ranks and nullities; these are different initial endowments and receive separate results. Neither regime establishes discovery of the entire mathematical representation from unstructured observations.

The middle cycles and boundaries are \(Z_1=\ker D_1\) and \(B_1=\operatorname {im}D_2\). The chain identity gives \(B_1\subseteq Z_1\), so the quotient \(H_1=Z_1/B_1\) is defined. Rank-nullity yields

Indeed, \(\dim Z_1=n_1-\operatorname {rank}D_1\) and \(\dim B_1=\operatorname {rank}D_2\); taking the quotient subtracts these dimensions. At the ends, \(\beta _0=n_0-\operatorname {rank}D_1\) and \(\beta _2=n_2-\operatorname {rank}D_2\). These elementary identities explain the evaluator's target and remain withheld as explicit answers where rediscovery is being measured. They are not new mathematical results.

Allowed changes include invertible changes of basis \(P_i\) in each space. They replace the matrices by

The product remains zero and the ranks remain unchanged. Another allowed change adjoins or removes a direct summand consisting of an identity map between two adjacent one-dimensional spaces, with zero maps elsewhere. That summand has zero homology in every degree. Direct sums add dimensions of homology, so these moves preserve all three \(\beta _i\). A candidate invariant can be challenged with new valid objects, basis changes and such elementary additions.

A target asks whether two presented objects are related by a sequence of these allowed moves. A positive certificate lists legal moves and their exact matrices, including inverses for basis changes and the displayed summand for a removal. A negative certificate supplies unequal homology dimensions with checked rank witnesses. A rank witness can give invertible row and column transformations, their inverses and a diagonal normal form with an identity block and zeros elsewhere; the checker verifies these matrix identities and counts the block size. Agreement of a proposed invariant on a few examples is insufficient, and equality of the dimensions alone is not accepted as a positive certificate. The agent must construct the required transformation or another certificate justified by the fixed mathematical checker.

A concrete sampler first draws uniformly from the finite set of nonnegative integer tuples \((h_0,h_1,h_2,r_1,r_2)\) satisfying the declared dimension cap, where

It builds a direct sum of zero-differential spaces of dimensions \(h_i\) in degree \(i\), \(r_1\) identity pairs in degrees one and zero, and \(r_2\) identity pairs in degrees two and one. Independently sampled invertible binary basis matrices scramble this presentation; uniform sampling by rejection from all binary square matrices is one exact choice. The resulting \(\beta _i=h_i\) are evaluator facts, not additional observations supplied to either agent. The distribution and sampling algorithm themselves are public, so reconstructing this decomposition is an admitted strategy.

Positive instances apply a sampled legal move sequence to an object, retaining that sequence privately. At each step the sampler chooses uniformly among the declared finite encodings of dimension-bounded legal moves; the identity move permits padding to the specified length. Negative instances draw two canonical tuples with different homology vectors and randomize their presentations independently. Their dimensions are matched where the chosen profile permits, and results are also stratified by dimension differences to detect easy size cues. Retained rank witnesses certify the labels. The mixture, move count, dimension profile and certificate limits are fixed before final seeds are sampled.

A single middle invariant is not complete even for this family. Objects concentrated in degree zero can have identical \(\beta _1=0\) and different \(\beta _0\), and hence cannot be related by the allowed moves. This provides a concrete counterexample to premature abstraction. A learner may retain the whole homology vector, refine its proposal or use direct algebraic reasoning; successful certification, rather than one preferred formula, determines the outcome.

This initial family has an efficient classical alternative. Gaussian elimination computes bases for cycles and boundaries and decomposes a finite complex over a field into homology summands and adjacent identity summands. It therefore supplies both the invariants and constructive transformations when appropriate. Its arithmetic and certificate costs must be measured as an admitted baseline. The setting can reveal how an agent develops and transfers a method, but cannot support a claim that all autonomous methods face a prohibitive search barrier merely because one language model initially fails it.