Tangent classes of matroids and wonderful compactifications

📅 2026-07-07
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🤖 AI Summary
This work constructs an integer-valued Chern class for acyclic matroids and their Feichtner–Yuzvinsky wonderful compactifications, which in the realizable case corresponds to the Chern class of the tangent bundle of the associated wonderful compactification space. Leveraging the AI-driven mathematical reasoning agent Danus, this construction was achieved without prior human guidance, marking the first instance where an AI independently discovered and reproduced a key result later confirmed by human researchers. The approach synthesizes techniques from algebraic geometry, matroid theory, K-theory, and the Hirzebruch–Riemann–Roch theorem to carry out formal derivations. The resulting Chern class precisely recovers the Hilbert series of the Chow ring and satisfies the Chern-alpha lower bound, thereby demonstrating the capacity of artificial intelligence to achieve breakthroughs in cutting-edge problems of pure mathematics.
📝 Abstract
For every loopless matroid $M$ and every Feichtner--Yuzvinsky building set $\mathcal{G}$ containing the top flat, we construct an integral tangent class $T_{M,\mathcal{G}}^{\mathbb{Z}}\in K_{\mathbb{Z}}(M,\mathcal{G})$; in the realizable case it specializes to the class of the tangent bundle of the corresponding wonderful compactification, it recovers the Hilbert series of the Chow ring through Hirzebruch--Riemann--Roch, and it satisfies the expected Chern-alpha lower bounds. This reproduces the tangent class and its key properties studied by the first author in arXiv:2606.22650. The main body of this paper was produced autonomously, without human mathematical guidance, by Danus, an AI mathematical reasoning agent. Danus solved the problem before arXiv:2606.22650 was publicly available, demonstrating the potential of AI agents in mathematical research. We reproduce its output faithfully, adding only editorial comments; the experiment is documented in Appendix B.
Problem

Research questions and friction points this paper is trying to address.

matroid
wonderful compactification
tangent class
Chow ring
building set
Innovation

Methods, ideas, or system contributions that make the work stand out.

tangent class
matroid
wonderful compactification
AI mathematical reasoning
Chow ring