16 research outputs found
Variable Sharing in Substructural Logics: an Algebraic Characterization
We characterize the non-trivial substructural logics having the variable sharing property as well as its strong version. To this end, we find the algebraic counterparts over varieties of these logical properties.The work was supported by the Austrian Science Fund (FWF): project I 1923-N25 (New perspectives on residuated posets)
Automated Synthesis of Tableau Calculi
This paper presents a method for synthesising sound and complete tableau
calculi. Given a specification of the formal semantics of a logic, the method
generates a set of tableau inference rules that can then be used to reason
within the logic. The method guarantees that the generated rules form a
calculus which is sound and constructively complete. If the logic can be shown
to admit finite filtration with respect to a well-defined first-order semantics
then adding a general blocking mechanism provides a terminating tableau
calculus. The process of generating tableau rules can be completely automated
and produces, together with the blocking mechanism, an automated procedure for
generating tableau decision procedures. For illustration we show the
workability of the approach for a description logic with transitive roles and
propositional intuitionistic logic.Comment: 32 page
A simplified lower bound for implicational logic
We present a streamlined and simplified exponential lower bound on the length
of proofs in intuitionistic implicational logic, adapted to Gordeev and
Haeusler's dag-like natural deduction.Comment: 31 page
Epimorphisms in varieties of subidempotent residuated structures
A commutative residuated lattice A is said to be subidempotent if the lower
bounds of its neutral element e are idempotent (in which case they naturally
constitute a Brouwerian algebra A*). It is proved here that epimorphisms are
surjective in a variety K of such algebras A (with or without involution),
provided that each finitely subdirectly irreducible algebra B in K has two
properties: (1) B is generated by lower bounds of e, and (2) the poset of prime
filters of B* has finite depth. Neither (1) nor (2) may be dropped. The proof
adapts to the presence of bounds. The result generalizes some recent findings
of G. Bezhanishvili and the first two authors concerning epimorphisms in
varieties of Brouwerian algebras, Heyting algebras and Sugihara monoids, but
its scope also encompasses a range of interesting varieties of De Morgan
monoids