Embedding lattices in the Kleene degrees
Under ZFC+CH, we prove that some lattices whose cardinalities do not exceed can be embedded in some local structures of Kleene degrees.
Embedding relations in the lattice of recursively enumerable sets.
Equality sets for recursively enumerable languages
We consider shifted equality sets of the form , where and are nonerasing morphisms and is a letter. We are interested in the family consisting of the languages , where is a coding and is a shifted equality set. We prove several closure properties for this family. Moreover, we show that every recursively enumerable language is a projection of a shifted equality set, that is, for some (nonerasing) morphisms and and a letter , where deletes the letters not in . Then we deduce...
Equality sets for recursively enumerable languages
We consider shifted equality sets of the form EG(a,g1,g2) = {ω | g1(ω) = ag2(ω)}, where g1 and g2 are nonerasing morphisms and a is a letter. We are interested in the family consisting of the languages h(EG(J)), where h is a coding and (EG(J)) is a shifted equality set. We prove several closure properties for this family. Moreover, we show that every recursively enumerable language L ⊆ A* is a projection of a shifted equality set, that is, L = πA(EG(a,g1,g2)) for some (nonerasing) morphisms g1...
Equivalence relations induced by extensional formulae: classification by means of a new fixed point property
Existential interpretation. II.
Extended primitive recursive functions
Extending regular expressions with homomorphic replacement
We define H- and EH-expressions as extensions of regular expressions by adding homomorphic and iterated homomorphic replacement as new operations, resp. The definition is analogous to the extension given by Gruska in order to characterize context-free languages. We compare the families of languages obtained by these extensions with the families of regular, linear context-free, context-free, and EDT0L languages. Moreover, relations to language families based on patterns, multi-patterns,...
Extension pathology in regressive isols
Extensions of -subsets to -subsets - existence versus constructability
Extensions to Regressive Isols.
e-степени гипериммунных ретрассируемых множеств.
Fibrations and recursivity
Finite alogorithmic procedures and computation theories.
Finite alogorithmic procedures and inductive definability.
Finite models and finitely many variables
This paper is a survey of results on finite variable logics in finite model theory. It focusses on the common underlying techniques that unite many such results.
Finiteness results on rewriting systems
First-order properties of trees, star-free expressions, and aperiodicity
Fixpoint alternation : arithmetic, transition systems, and the binary tree
Fixpoint alternation: arithmetic, transition systems, and the binary tree
We provide an elementary proof of the fixpoint alternation hierarchy in arithmetic, which in turn allows us to simplify the proof of the modal mu-calculus alternation hierarchy. We further show that the alternation hierarchy on the binary tree is strict, resolving a problem of Niwiński.