scholarly journals Poincaré Series of some Hypergraph Algebras

2013 ◽  
Vol 112 (1) ◽  
pp. 5 ◽  
Author(s):  
E. Emtander ◽  
R. Fröberg ◽  
F. Mohammadi ◽  
S. Moradi
Keyword(s):  
Betti Numbers ◽  
Poincaré Series ◽  
Poincare Series ◽  
Graded Betti Numbers ◽  
Graph Algebra ◽  
Wheel Graph

A hypergraph $H=(V,E)$, where $V=\{x_1,\ldots,x_n\}$ and $E\subseteq 2^V$ defines a hypergraph algebra $R_H=k[x_1,\ldots, x_n]/(x_{i_1}\cdots x_{i_k}; \{i_1,\ldots,i_k\}\in E)$. All our hypergraphs are $d$-uniform, i.e., $|e_i|=d$ for all $e_i\in E$. We determine the Poincaré series $P_{R_H}(t)=\sum_{i=1}^\infty\dim_k\mathrm{Tor}_i^{R_H}(k,k)t^i$ for some hypergraphs generalizing lines, cycles, and stars. We finish by calculating the graded Betti numbers and the Poincaré series of the graph algebra of the wheel graph.

Poincaré series of Milnor algebras and free arrangements

2010 ◽  
Vol 47 (4) ◽  
pp. 513-521
Author(s):  
Shahid Ahmad
Keyword(s):  
Hyperplane Arrangement ◽  
Betti Numbers ◽  
Poincaré Series ◽  
Poincare Series ◽  
Complex Hyperplane

We show that for a free complex hyperplane arrangement \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage{bbm} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\mathcal{A}$$ \end{document}: f = 0, the Poincaré series of the graded Milnor algebra M(f) and the Betti numbers of the arrangement complement M(\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage{bbm} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\mathcal{A}$$ \end{document}) determine each other. Examples show that this is false if we drop the freeness assumption.

scholarly journals Extremal Betti Numbers of Some Cohen–Macaulay Binomial Edge Ideals

2021 ◽  
Vol 28 (03) ◽  
pp. 415-430
Author(s):  
Carla Mascia ◽  
Giancarlo Rinaldo
Keyword(s):  
Betti Numbers ◽  
Bipartite Graphs ◽  
Poincaré Series ◽  
Poincare Series ◽  
Edge Ideals

We provide the regularity and the Cohen–Macaulay type of binomial edge ideals of Cohen–Macaulay cones, and we show the extremal Betti numbers of some classes of Cohen–Macaulay binomial edge ideals: Cohen–Macaulay bipartite and fan graphs. In addition, we compute the Hilbert–Poincaré series of the binomial edge ideals of some Cohen–Macaulay bipartite graphs.

scholarly journals Poincaré series, 3d gravity and averages of rational CFT

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Viraj Meruliya ◽  
Sunil Mukhi ◽  
Palash Singh
Keyword(s):  
Poincaré Series ◽  
Simons Theory ◽  
Partition Functions ◽  
Moody Algebra ◽  
Modular Invariant ◽  
Poincare Series ◽  
Single Genus ◽  
3D Gravity ◽  
Chern Simons ◽  
Chern Simons Theory

Abstract We investigate the Poincaré series approach to computing 3d gravity partition functions dual to Rational CFT. For a single genus-1 boundary, we show that for certain infinite sets of levels, the SU(2)k WZW models provide unitary examples for which the Poincaré series is a positive linear combination of two modular-invariant partition functions. This supports the interpretation that the bulk gravity theory (a topological Chern-Simons theory in this case) is dual to an average of distinct CFT’s sharing the same Kac-Moody algebra. We compute the weights of this average for all seed primaries and all relevant values of k. We then study other WZW models, notably SU(N)1 and SU(3)k, and find that each class presents rather different features. Finally we consider multiple genus-1 boundaries, where we find a class of seed functions for the Poincaré sum that reproduces both disconnected and connected contributions — the latter corresponding to analogues of 3-manifold “wormholes” — such that the expected average is correctly reproduced.

Two Applications of Change of Rings Theorems for Poincare-Series

1979 ◽  
Vol 73 (2) ◽  
pp. 163
Author(s):  
Jurgen Herzog ◽  
Manfred Steurich
Keyword(s):  
Poincaré Series ◽  
Poincare Series

scholarly journals Poincaré series for filtrations defined by discrete valuations with arbitrary center

2013 ◽  
Vol 377 ◽  
pp. 66-75 ◽  
Author(s):  
Antonio Campillo ◽  
Ann Lemahieu
Keyword(s):  
Poincaré Series ◽  
Poincare Series

Semigroup and Poincaré series for a finite set of divisorial valuations

2014 ◽  
Vol 28 (1) ◽  
pp. 191-225 ◽  
Author(s):  
Leen Van Langenhoven ◽  
Willem Veys
Keyword(s):  
Poincaré Series ◽  
Poincare Series ◽  
Finite Set ◽  
Divisorial Valuations

Weakly Polymatroidal Ideals

2006 ◽  
Vol 13 (04) ◽  
pp. 711-720 ◽  
Author(s):  
Masako Kokubo ◽  
Takayuki Hibi
Keyword(s):  
Betti Numbers ◽  
Partially Ordered Sets ◽  
Finite Sequence ◽  
Ordered Sets ◽  
Partially Ordered ◽  
Graded Betti Numbers ◽  
Linear Resolution ◽  
Fundamental Fact ◽  
Polymatroidal Ideals ◽  
Polymatroidal Ideal

The concept of the weakly polymatroidal ideal, which generalizes both the polymatroidal ideal and the prestable ideal, is introduced. A fundamental fact is that every weakly polymatroidal ideal has a linear resolution. One of the typical examples of weakly polymatroidal ideals arises from finite partially ordered sets. We associate each weakly polymatroidal ideal with a finite sequence, alled the polymatroidal sequence, which will be useful for the computation of graded Betti numbers of weakly polymatroidal ideals as well as for the construction of weakly polymatroidal ideals.

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