15 citations · 34 across the 8 of their papers we have counts for
9 papers
Semilinear De Morgan monoids and epimorphisms
Johann J. Wannenburg, James G. Raftery
A representation theorem is proved for De Morgan monoids that are (i) semilinear, i.e., subdirect products of totally ordered algebras, and (ii) negatively generated, i.e., generat…
The Algebraic Significance of Weak Excluded Middle Laws
T. Lávička, T. Moraschini, J. G. Raftery
For (finitary) deductive systems, we formulate a signature-independent abstraction of the \emph{weak excluded middle law} (WEML), which strengthens the existing general notion of a…
Epimorphisms in varieties of residuated structures
G. Bezhanishvili, T. Moraschini, J. Raftery
It is proved that epimorphisms are surjective in a range of varieties of residuated structures, including all varieties of Heyting or Brouwerian algebras of finite depth, and all v…
On prevarieties of logic
T. Moraschini, J. G. Raftery
It is proved that every prevariety of algebras is categorically equivalent to a "prevariety of logic", i.e., to the equivalent algebraic semantics of some sentential deductive syst…
Singly generated quasivarieties and residuated structures
T. Moraschini, J. G. Raftery, J. J. Wannenburg
A quasivariety K of algebras has the joint embedding property (JEP) iff it is generated by a single algebra A. It is structurally complete iff the free countably generated algebra…
Epimorphisms in varieties of subidempotent residuated structures
T. Moraschini, J. G. Raftery, J. J. Wannenburg
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 alg…
Varieties of De Morgan monoids: covers of atoms
T. Moraschini, J. G. Raftery, J. J. Wannenburg
The variety DMM of De Morgan monoids has just four minimal subvarieties. The join-irreducible covers of these atoms in the subvariety lattice of DMM are investigated. One of the tw…
Varieties of De Morgan monoids: minimality and irreducible algebras
T. Moraschini, J. G. Raftery, J. J. Wannenburg
It is proved that every finitely subdirectly irreducible De Morgan monoid A (with neutral element e) is either (i) a Sugihara chain in which e covers not(e) or (ii) the union of an…
Epimorphisms, definability and cardinalities
T. Moraschini, J. G. Raftery, J. J. Wannenburg
Generalizing a theorem of Campercholi, we characterize, in syntactic terms, the ranges of epimorphisms in an arbitrary class of similar first-order structures (as opposed to an ele…