Galina Jirásková

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We study the state complexity of regular operations in the class of ideal languages. A language L ⊆ Σ * is a right (left) ideal if it satisfies L = LΣ * (L = Σ * L). It is a two-sided ideal if L = Σ * LΣ * , and an all-sided ideal if L = Σ * L, the shuffle of Σ * with L. We prefer the term " quotient complexity " instead of " state complexity " , and we use(More)
A language L is prefix-closed if, whenever a word w is in L, then every prefix of w is also in L. We define suffix-, factor-, and subword-closed languages in an analogous way, where by factor we mean contiguous subsequence, and by subword we mean scattered subsequence. We study the state complexity (which we prefer to call quotient complexity) of operations(More)
We continue the investigation of union-free regular languages that are described by regular expressions without the union operation. We also define deterministic union-free languages as languages accepted by one-cycle-free-path deterministic finite automata, and show that they are properly included in the class of union-free languages. We prove that(More)