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Möbius Inversion and Duality for Summations of Stable Graphs

Zhiyuan Wang, Jian Zhou

Abstract

Using the stratifications of Deligne-Mumford moduli spaces $\overline{\mathcal M}_{g,n}$ indexed by stable graphs, we introduce a partially ordered set of stable graphs by defining a partial ordering on the set of connected stable graphs of genus $g$ with $n$ external edges. By modifying the usual definition of zeta function and Möbius function of a poset, we introduce generalized ($\mathbb Q$-valued) zeta function and generalized ($\mathbb Q$-valued) Möbius function of the poset of stable graphs. We use them to proved a generalized Möbius inversion formula for functions on the poset of stable graphs. Two applications related to duality in earlier work are also presented.

Möbius Inversion and Duality for Summations of Stable Graphs

Abstract

Using the stratifications of Deligne-Mumford moduli spaces indexed by stable graphs, we introduce a partially ordered set of stable graphs by defining a partial ordering on the set of connected stable graphs of genus with external edges. By modifying the usual definition of zeta function and Möbius function of a poset, we introduce generalized (-valued) zeta function and generalized (-valued) Möbius function of the poset of stable graphs. We use them to proved a generalized Möbius inversion formula for functions on the poset of stable graphs. Two applications related to duality in earlier work are also presented.
Paper Structure (20 sections, 13 theorems, 99 equations)

This paper contains 20 sections, 13 theorems, 99 equations.

Key Result

Lemma 2.1

Denote by $\Gamma\in {\mathcal{G}}_{g,n}^c$ a stable graph (in the usual sense) without names, and $S_\Gamma$ the set of stable graph $\Gamma'$ with names on external edges, such that $\Gamma$ can be obtained from $\Gamma'$ by forgetting all the names. Then we have:

Theorems & Definitions (43)

  • Definition 2.1: wz
  • Example 2.1
  • Example 2.2
  • Example 2.3
  • Lemma 2.1: wz2
  • Definition 2.2: wz2
  • Example 2.4
  • Theorem 2.1: wz2
  • Theorem 2.2: wz2
  • Theorem 3.1: ro
  • ...and 33 more