12,916 research outputs found
More Structural Characterizations of Some Subregular Language Families by Biautomata
We study structural restrictions on biautomata such as, e.g., acyclicity,
permutation-freeness, strongly permutation-freeness, and orderability, to
mention a few. We compare the obtained language families with those induced by
deterministic finite automata with the same property. In some cases, it is
shown that there is no difference in characterization between deterministic
finite automata and biautomata as for the permutation-freeness, but there are
also other cases, where it makes a big difference whether one considers
deterministic finite automata or biautomata. This is, for instance, the case
when comparing strongly permutation-freeness, which results in the family of
definite language for deterministic finite automata, while biautomata induce
the family of finite and co-finite languages. The obtained results nicely fall
into the known landscape on classical language families.Comment: In Proceedings AFL 2014, arXiv:1405.527
Maximally Atomic Languages
The atoms of a regular language are non-empty intersections of complemented
and uncomplemented quotients of the language. Tight upper bounds on the number
of atoms of a language and on the quotient complexities of atoms are known. We
introduce a new class of regular languages, called the maximally atomic
languages, consisting of all languages meeting these bounds. We prove the
following result: If L is a regular language of quotient complexity n and G is
the subgroup of permutations in the transition semigroup T of the minimal DFA
of L, then L is maximally atomic if and only if G is transitive on k-subsets of
1,...,n for 0 <= k <= n and T contains a transformation of rank n-1.Comment: In Proceedings AFL 2014, arXiv:1405.527
Generalized Results on Monoids as Memory
We show that some results from the theory of group automata and monoid
automata still hold for more general classes of monoids and models. Extending
previous work for finite automata over commutative groups, we demonstrate a
context-free language that can not be recognized by any rational monoid
automaton over a finitely generated permutable monoid. We show that the class
of languages recognized by rational monoid automata over finitely generated
completely simple or completely 0-simple permutable monoids is a semi-linear
full trio. Furthermore, we investigate valence pushdown automata, and prove
that they are only as powerful as (finite) valence automata. We observe that
certain results proven for monoid automata can be easily lifted to the case of
context-free valence grammars.Comment: In Proceedings AFL 2017, arXiv:1708.0622
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