25 citations · 40 across the 7 of their papers we have counts for
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Complexity in the interdefinability of timelike, lightlike and spacelike relatedness of Minkowski spacetime
Hajnal Andréka, Judit X. Madarász, István Németi +1
Interdefinability of timelike, lightlike and spacelike relatedness of Minkowski spacetime is investigated in detail in the paper, with the aim of finding the simplest definitions.…
Two-variable logic has weak, but not strong, Beth definability
H. Andréka, I. Németi
We prove that the two-variable fragment of first-order logic has the weak Beth definability property. This makes the two-variable fragment a natural logic separating the weak and t…
A representation theorem for measurable relation algebras with cyclic groups
Hajnal Andréka, Steven Givant
A relation algebra is measurable if the identity element is a sum of atoms, and the square x;1;x of each subidentity atom x is a sum of non-zero functional elements. These function…
Free algebras of discriminator varieties generated by finite algebras are atomic
H. Andréka, I. Németi
We prove that all definable pre-orders are atomic, in a finitely generated free algebra of a discriminator variety of finite similarity type which is generated by its finite member…
How many varieties of cylindric algebras
H. Andréka, I. Németi
Cylindric algebras, or concept algebras in another name, form an interface between algebra, geometry and logic; they were invented by Alfred Tarski around 1947. We prove that there…