We study the canonical weak distributive law $\delta$ of powerset monad over semimodule for a certain class semirings containing, in particular, positive semifields. For this subclass we characterise as convex closure free set. Using abstract theory laws, compose and monads via $\delta$, obtaining subsets semimodule.

Operators that systematically produce more precise abstract interpretations from simpler ones are interesting. In this paper we present a formal study of one such operator: the powerset. The main achievements of the paper are described below: • A formal definition of the powerset operator is given. For any given abstract interpretation D = 〈D, o1, . . . , ok〉, where D is the abstract domain and...

Kripke semantics plays a fundamental role for modal logics where it often provides modular semantics allowing a clear treatment of various logics related by the addition of axioms or connectives. Kripke semantics is also the “natural semantics” for classical modal logic in the sense that it is given by the representation theory for modal algebras. The algebraic structure corresponding to a trad...

Hereditarily finite (HF) set theory provides a standard universe of sets, but with no infinite sets. Its utility is demonstrated through a formalisation of the theory of regular languages and finite automata, including the Myhill-Nerode theorem and Brzozowski’s minimisation algorithm. The states of an automaton are HF sets, possibly constructed by product, sum, powerset and similar operations.

A set A of positive integers is called a coprime Diophantine powerset if the shifted product ab + 1 of two different elements a and b of A is always a pure power, and the occurring pure powers are all coprime. We prove that each coprime Diophantine powerset A ⊂ {1, . . . , N} has |A| 8000 log N/ log log N for sufficiently large N. The proof combines results from extremal graph theory with numbe...

Let CABA be the category of complete and atomic boolean algebras homomorphisms, let CSL meet-semilattices meet-homomorphisms. We show that forgetful functor from to has a left adjoint. This allows us describe an endofunctor H on such Alg(H) for is dually equivalent Coalg(P) coalgebras powerset P Set. As consequence, we derive Thomason duality Tarski duality, thus paralleling how J\'onsson-Tarsk...

Church’s Problem, stated fifty years ago, asks for a finitestate machine that realizes the transformation of an infinite sequence α into an infinite sequence β such that a requirement on (α, β), expressed in monadic second-order logic, is satisfied. We explain how three fundamental techniques of automata theory play together in a solution of Church’s Problem: Determinization (starting from the ...

We analyze structure theories of the power-set of ω1 and compare them relative to Cantor’s Continuum Problem. We also compare these theories with the structure theory of the powerset of ω under the assumption of the axiom of definable determinacy.

It is known that implications in powerset-based closure systems correspond to Horn approximations in propositional logic frameworks. Here we focus on the problem of implications between injective partial orders. We set up the definitions that allow one to apply standard constructions of implications, and formally characterize the propositional theory obtained. We describe also some experimental...