3 papers
math.LO2025
Permutations, substitutions and finite axiomatizability
Hajnal Andréka, Zalán Gyenis, István Németi
Algebras of relations form an algebraic framework for the study of logical systems, extending the correspondence between Boolean algebras and propositional logic. Tarski's represen…
gr-qc2025
An extendible spacetime without closed timelike curves whose every extension contains closed timelike curves
H. Andréka, J. Madarász, J. Manchak +2
By removing a fractal from time-rolled Minkowski spacetime, we construct an extendible spacetime without closed timelike curves whose every extension contains closed timelike curve…
math.LO2025
Substitutions of variables are finitely axiomatizable over quantifications and permutations
Hajnal Andréka, Zalán Gyenis, István Németi
This paper proves that the equational theory of the class of representable polyadic algebras is finitely axiomatizable over its substitution-free reduct ,…