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We describe the outer automorphism group of a one-ended fundamental group of a graph of groups, when edge groups are cyclic, and vertex groups are torsion-free with cyclic centralizers. We show that in this case the outer automorphism group…

Group Theory · Mathematics 2025-07-23 Dario Ascari , Montserrat Casals-Ruiz , Ilya Kazachkov

Using the theory of group action, we first introduce the concept of the automorphism group of an exponential family or a graphical model, thus formalizing the general notion of symmetry of a probabilistic model. This automorphism group…

Artificial Intelligence · Computer Science 2012-07-24 Hung Hai Bui , Tuyen N. Huynh , Sebastian Riedel

We consider a binary response which is potentially affected by a set of continuous variables. Of special interest is the causal effect on the response due to an intervention on a specific variable. The latter can be meaningfully determined…

Methodology · Statistics 2020-09-11 Federico Castelletti , Guido Consonni

We propose a Bayesian approximate inference method for learning the dependence structure of a Gaussian graphical model. Using pseudo-likelihood, we derive an analytical expression to approximate the marginal likelihood for an arbitrary…

Machine Learning · Statistics 2017-04-13 Janne Leppä-aho , Johan Pensar , Teemu Roos , Jukka Corander

Let $G$ be $2$-generated group. The generating graph of $\Gamma(G)$ is the graph whose vertices are the elements of $G$ and where two vertices $g$ and $h$ are adjacent if $G=\langle g,h\rangle$. This graph encodes the combinatorial…

Group Theory · Mathematics 2020-06-15 Scott Harper , Andrea Lucchini

In multivariate time series analysis, understanding the underlying causal relationships among variables is often of interest for various applications. Directed acyclic graphs (DAGs) provide a powerful framework for representing causal…

Methodology · Statistics 2025-07-30 Arkaprava Roy , Anindya Roy , Subhashis Ghosal

Gaussian graphical models are semi-algebraic subsets of the cone of positive definite covariance matrices. They are widely used throughout natural sciences, computational biology and many other fields. Computing the vanishing ideal of the…

Algebraic Geometry · Mathematics 2020-09-22 Pratik Misra , Seth Sullivant

In this paper we study the algebra of graph invariants, focusing mainly on the invariants of simple graphs. All other invariants, such as sorted eigenvalues, degree sequences and canonical permutations, belong to this algebra. In fact,…

Combinatorics · Mathematics 2008-01-30 Tomi Mikkonen , Xavier Buchwalder

The \emph{power graph} $P(G)$ of a group $G$ is the graph whose vertex set is $G$, with $x$ and $y$ joined if one is a power of the other; the \emph{directed power graph} $\vec{P}(G)$ has the same vertex set, with an arc from $x$ to $y$ if…

Group Theory · Mathematics 2019-05-31 Peter J. Cameron , Horacio Guerra , Šimon Jurina

We show that almost all circulant graphs have automorphism groups as small as possible. Of the circulant graphs that do not have automorphism group as small as possible, we give some families of integers such that it is not true that almost…

Combinatorics · Mathematics 2012-03-06 Soumya Bhoumik , Edward Dobson , Joy Morris

We introduce a novel class of labeled directed acyclic graph (LDAG) models for finite sets of discrete variables. LDAGs generalize earlier proposals for allowing local structures in the conditional probability distribution of a node, such…

Machine Learning · Statistics 2014-11-12 Johan Pensar , Henrik Nyman , Timo Koski , Jukka Corander

We consider the problem of Bayesian causal discovery for the standard model of linear structural equations with equivariant Gaussian noise. A uniform prior is placed on the space of directed acyclic graphs (DAGs) over a fixed set of…

Statistics Theory · Mathematics 2025-07-23 Valentinian Lungu , Joni Shaska , Ioannis Kontoyiannis , Urbashi Mitra

Directed acyclic graph (DAG) models are widely used to represent causal relationships among random variables in many application domains. This paper studies a special class of non-Gaussian DAG models, where the conditional variance of each…

Machine Learning · Statistics 2021-11-03 Wei Zhou , Xin He , Wei Zhong , Junhui Wang

Time series graphical models have recently received considerable attention for characterizing (conditional) dependence structures in multivariate time series. In many applications, the multivariate series exhibit variable-partitioned…

Methodology · Statistics 2026-04-09 Qin Fang , Xinghao Qiao , Zihan Wang

In this article we generalize a theorem of Benson for generalized quadrangles to strongly regular graphs and directed strongly regular graphs. The main result provides numerical restrictions on the number of fixed vertices and the number of…

Combinatorics · Mathematics 2014-11-14 S. De Winter , E. Kamischke , Z. Wang

We consider multivariate centered Gaussian models for the random vector $(Z^1,\ldots, Z^p)$, whose conditional structure is described by a homogeneous graph and which is invariant under the action of a permutation subgroup. The following…

Statistics Theory · Mathematics 2022-09-22 Piotr Graczyk , Hideyuki Ishi , Bartosz Kołodziejek

Let $T$ be a tree and $e$ an edge in $T$. If $C$ is a component of $T\setminus e$ and both $C$ and its complement are infinite we say that $C$ is a half-tree. The main result of this paper is that if $G$ is a closed subgroup of the…

Group Theory · Mathematics 2012-09-18 Rögnvaldur G. Möller , Jan Vonk

We consider distributed inference in social networks where a phenomenon of interest evolves over a given social interaction graph, referred to as the \emph{social digraph}. For inference, we assume that a network of agents monitors certain…

Social and Information Networks · Computer Science 2015-06-18 Mohammadreza Doostmohammadian , Usman A. Khan

Dependency knowledge of the form "x is independent of y once z is known" invariably obeys the four graphoid axioms, examples include probabilistic and database dependencies. Often, such knowledge can be represented efficiently with…

Artificial Intelligence · Computer Science 2013-04-10 Tom S. Verma , Judea Pearl

We introduce a general framework for undirected graphical models. It generalizes Gaussian graphical models to a wide range of continuous, discrete, and combinations of different types of data. The models in the framework, called exponential…

Statistics Theory · Mathematics 2019-06-18 Rui Zhuang , Noah Simon , Johannes Lederer