arXiv subjects

Somayeh Chopoghloo

Publications and source records attributed to Somayeh Chopoghloo.

5 recordsLinked to original sources

arXiv2026

A Set-Theoretic Translation of Modal Logic via Forcing

We develop a set-theoretic translation of a normal modal extension $T_m$ of a recursively axiomatizable first-order theory $T$. We first pass to the Henkin expansion of the underlying language by adding witness constants and work with the sentence algebra of this expansion. The translation is constructed using the corresponding Lindenbaum-Tarski algebra, the Stone space of its ultrafilters, and quotient forcing by a $\sigma$-ideal of Borel sets; in particular, the meager ideal yields Cohen forcing and the null ideal yields the random forcing. In a Boolean-valued universe, we interpret the modal operator $\Box$ by membership of the Boolean value of the translated formula in a suitable filter name. We prove that this translation is sound and complete: a modal formula is provable in $T_m$ if and only if its set-theoretic translation is forced in every associated interpretation. We then build Kripke frames and models from generic extensions and show that the forcing interpretation of $\Box$ agrees with quantification over the corresponding accessibility relation. As a consequence, we obtain completeness with respect to the resulting Kripke models.

math.LO↗

arXiv2026

Goldblatt-Thomason Theorem for Probability Logic

Probability logic (PL) extends propositional logic with countably many probability operators, one for each rational number between 0 and 1. The formulas of this logic are interpreted over the class of Markov processes, i.e., structures of the form $(\Omega, \Sigma, T)$, where$(\Omega, \Sigma)$ is a measurable space and $T$ is a Markov kernel. The main contribution of this paper is the establishment of the Goldblatt-Thomason theorem for probability logic. As an application, we show that the class of Harsanyi type spaces is definable in PL. Moreover, we obtain some variants of the Goldblatt-Thomason theorem for specific subclasses of Markov processes.

cs.LO↗

arXiv2026

Completeness and Incompleteness for Expanding G\"odel-L\"ob Logics

Expanding products of modal logics are bimodal logics obtained from the combination of a `horizontal component' logic and a `vertical component' logic, lying between the fusion and the Cartesian product of the two logics. Gabelaia et al. showed that expanding products are often decidable when the first component is Noetherian, although their methods are semantical and do not yield complete axiomatisations. They do, however, propose a candidate, dubbed the expanding commutator of the two logics and known to be complete in many `non-Noetherian' cases. In this paper, we consider various expanding products of modal logics whose vertical component is $\sf GL$. We show that the standard axiomatisation is complete when the horizontal component is either $ {\sf K4}$ or $ {\sf GL} $, but incomplete when it is ${\sf Grz}$ or any logic between ${\sf K4.3}$ and ${\sf Grz.3}$, thus yielding a partial solution to a question posed by Gabelaia et al. more than two decades ago.

math.LO↗

arXiv2024

Dynamic Probability Logic: Decidability & Computability

In this article, the decidability and computability issues of dynamic probability logic (DPL) are addressed. Firstly, a proof system $\mathcal{H}_{DPL}$ is introduced for DPL and shown that it is weakly complete. Furthermore, this logic has the finite model property and so is decidable. Secondly, a strongly complete proof system HDPL is presented for DPL and proved that its canonical model is a computable structure.

cs.LO↗

arXiv2024

Dynamic Probability Logics: Axiomatization & Definability

We first study probabilistic dynamical systems from logical perspective. To this purpose, we introduce the finitary dynamic probability logic} ($\mathsf{DPL}$), as well as its infinitary extension $\mathsf{DPL}_{ω_1}\!$. Both these logics extend the (modal) probability logic ($\mathsf{PL}$) by adding a temporal-like operator $\bigcirc$ (denoted as dynamic operator) which describes the dynamic part of the system. We subsequently provide Hilbert-style axiomatizations for both $\mathsf{DPL}$ and $\mathsf{DPL}_{ω_1}\!$. We show that while the proposed axiomatization for $\mathsf{DPL}$ is strongly complete, the axiomatization for the infinitary counterpart supplies strong completeness for each countable fragment $\mathbb{A}$ of $\mathsf{DPL}_{ω_1}\!$. Secondly, our research focuses on the (frame) definability of important properties of probabilistic dynamical systems such as measure-preserving, ergodicity and mixing within $\mathsf{DPL}$ and $\mathsf{DPL}_{ω_1}$. Furthermore, we consider the infinitary probability logic $\mathsf{InPL}_{ω_1}$ (probability logic with initial probability distribution) by disregarding the dynamic operator. This logic studies {\em Markov processes with initial distribution}, i.e. mathematical structures of the form $\langle Ω, \mathcal{A}, T, π\rangle$ where $\langle Ω, \mathcal{A}\rangle$ is a measurable space, $T: Ω\times \mathcal{A}\to [0, 1]$ is a Markov kernel and $π: \mathcal{A}\to [0, 1]$ is a $σ$-additive probability measure. We prove that many natural stochastic properties of Markov processes such as stationary, invariance, irreducibility and recurrence are $\mathsf{InPL}_{ω_1}$-definable.

math.LO↗