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5 votes
0 answers
136 views

Face structures of chain polytopes

For a finite poset $P$ the chain polytope $\mathscr C(P)\subset\mathbb{R}^P$ consists of such $g$ that $g(p)\ge 0$ for all $p\in P$ and $$g(p_1)+\ldots+g(p_n)\le 1$$ for any chain $p_1<\ldots<p_n$. I …
Igor Makhlin's user avatar
  • 3,513
5 votes
1 answer
246 views

Infinitely many initial ideals for non-Artinian monomial orders?

Consider the polynomial ring $R=\mathbb Z[x_1,\ldots,x_n]$ and an ideal $I\subset R$. Let $<$ be a monomial order, i.e. a total order on the set of monomials in $R$ such that for any monomials $a$, $b …
Igor Makhlin's user avatar
  • 3,513
6 votes
0 answers
181 views

Natural bijection between join- and meet-irreducibles in modular lattices?

A well known property of finite modular lattices is that they have the same number of join-irreducible and meet-irreducible elements. I was wondering if there exists a natural bijection between these …
Igor Makhlin's user avatar
  • 3,513
6 votes
2 answers
276 views

"Minimal" connected matroids

I'm interested in connected matroids $M$ on the ground set $[n]$ for which there is no connected matroid on $[n]$ of the same rank but with a strictly smaller set of bases (by inclusion). Equivalently …
Igor Makhlin's user avatar
  • 3,513
2 votes

Birkhoff's representation theorem vs matroid-geometric lattice correspondence

I think I might've stumbled upon the answer I was looking for. It's the correspondence between interval greedoids and semimodular lattices. An interval greedoid is a pair $(E,\mathcal F)$ where $\math …
Igor Makhlin's user avatar
  • 3,513
14 votes
5 answers
853 views

Birkhoff's representation theorem vs matroid-geometric lattice correspondence

This question is motivated by the superficial observation that Birkhoff's representation theorem and the cryptomorphism between matroids and geometric lattices are sort of similar. The former says tha …
Igor Makhlin's user avatar
  • 3,513
1 vote

Birkhoff's representation theorem vs matroid-geometric lattice correspondence

I learned that there is at least one precise answer to this exact question (more precise than my previous answer). The bijection between finite posets and finite distributive lattices and the bijectio …
Igor Makhlin's user avatar
  • 3,513