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We present an effective algorithm for detecting automorphic orbits in free groups, as well as a number of algorithmic improvements of train tracks for free group automorphisms.

Group Theory · Mathematics 2010-06-25 Peter Brinkmann

Given a free group of rank r >= 3 and two exponentially growing outer automorphisms {\psi} and {\phi} with dual lamination pairs {\Lambda^\pm}_{\psi} and {\Lambda^\pm}_{\phi} associated to them, which satisfy a notion of independence…

Group Theory · Mathematics 2015-11-26 Pritam Ghosh

We establish the following non-abelian analogue of the Fundamental Theorem of Projective Geometry: the natural map from ${\rm{Aut}}(F_n)$ to the automorphism group of the free-factor complex $\mathcal{AF}_n$ is an isomorphism. We also prove…

Group Theory · Mathematics 2023-06-12 Mladen Bestvina , Martin R Bridson

An infinite iterated function system (IIFS) is a countable collection of contraction maps on a compact metric space. In this paper we study the conditions under which the attractor of a such system admits a parameterization by a continuous…

Metric Geometry · Mathematics 2024-04-09 Eve Shaw , Vyron Vellis

We give an algorithm to determine whether Wilf's conjecture holds for all numerical semigroups with a given multiplicity $m$, and use it to prove Wilf's conjecture holds whenever $m \le 18$. Our algorithm utilizes techniques from polyhedral…

Combinatorics · Mathematics 2019-07-23 Winfried Bruns , Pedro Garcia-Sanchez , Christopher O'Neill , Dane Wilburne

The paper provides results regarding the computational complexity of hybrid system identification. More precisely, we focus on the estimation of piecewise affine (PWA) maps from input-output data and analyze the complexity of computing a…

Machine Learning · Statistics 2015-09-09 Fabien Lauer

Lubiw showed that several variants of Graph Isomorphism are NP-complete, where the solutions are required to satisfy certain additional constraints [SICOMP 10, 1981]. One of these, called Isomorphism With Restrictions, is to decide for two…

Computational Complexity · Computer Science 2017-09-29 V. Arvind , Johannes Köbler , Sebastian Kuhnert , Jacobo Toran

The avoidability, or unavoidability of patterns in words over finite alphabets has been studied extensively. A word (pattern) over a finite set is said to be unavoidable if, for all but finitely many words, there exists a morphism mapping…

Formal Languages and Automata Theory · Computer Science 2019-07-16 Paul Sauer

We study the degree of irreducible morphisms in any Auslander-Reiten component of a finite dimensional algebra over an algebraically closed field. We give a characterization for an irreducible morphism to have finite left (or right) degree.…

Representation Theory · Mathematics 2016-05-11 Patrick Le Meur , Claudia Chaio , Sonia Trepode

We revisit the problem of deciding whether a finitely generated subgroup H is a free factor of a given free group F. Known algorithms solve this problem in time polynomial in the sum of the lengths of the generators of H and exponential in…

Group Theory · Mathematics 2008-08-01 Pedro Silva , Pascal Weil

It is well-known that typability, type inhabitation and type inference are undecidable in the Girard-Reynolds polymorphic system F. It has recently been proven that type inhabitation remains undecidable even in the predicative fragment of…

Logic in Computer Science · Computer Science 2023-06-22 M. Clarence Protin , Gilda Ferreira

Measures generated by Iterated Function Systems composed of uncountably many one--dimensional affine maps are studied. We present numerical techniques as well as rigorous results that establish whether these measures are absolutely or…

Dynamical Systems · Mathematics 2011-06-23 Giorgio Mantica

We show that the question whether a term is typable is decidable for type systems combining inclusion polymorphism with parametric polymorphism provided the type constructors are at most unary. To prove this result we first reduce the…

Logic in Computer Science · Computer Science 2007-05-23 Sabine Glesner , Karl Stroetmann

A map $\phi:M_m(\bC)\to M_n(\bC)$ is decomposable if it is of the form $\phi=\phi_1+\phi_2$ where $\phi_1$ is a CP map while $\phi_2$ is a co-CP map. It is known that if $m=n=2$ then every positive map is decomposable. Given an extremal…

Functional Analysis · Mathematics 2007-05-23 Wladyslaw A. Majewski , Marcin Marciniak

This article presents a formal model demonstrating that genuine autonomy, the ability of a system to self-regulate and pursue objectives, fundamentally implies computational unpredictability from an external perspective. we establish…

Artificial Intelligence · Computer Science 2025-09-17 Poria Azadi

We prove that the isomorphism of scattered tree automatic linear orders as well as the existence of automorphisms of scattered word automatic linear orders are undecidable. For the existence of automatic automorphisms of word automatic…

Logic in Computer Science · Computer Science 2012-04-26 Dietrich Kuske

As AI systems are used in high-stakes applications, ensuring interpretability is crucial. Mechanistic Interpretability (MI) aims to reverse-engineer neural networks by extracting human-understandable algorithms to explain their behavior.…

Machine Learning · Computer Science 2025-03-03 Maxime Méloux , Silviu Maniu , François Portet , Maxime Peyrard

Full waveform inversion (FWI) is an iterative identification process that serves to minimize the misfit of model-based simulated and experimentally measured wave field data, with the goal of identifying a field of parameters for a given…

Computational Engineering, Finance, and Science · Computer Science 2023-12-05 Tim Bürchner , Philipp Kopp , Stefan Kollmannsberger , Ernst Rank

We call a group $G$ {\it algorithmically finite} if no algorithm can produce an infinite set of pairwise distinct elements of $G$. We construct examples of recursively presented infinite algorithmically finite groups and study their…

Group Theory · Mathematics 2010-12-09 A. Myasnikov , D. Osin

In this paper we study the existence of at least one non-inner automorphism of order p of a finite thin p-group, for any prime p.

Group Theory · Mathematics 2016-04-26 Marco Ruscitti , Leire Legarreta