From regular expressions to smaller NFAs
نویسندگان
چکیده
منابع مشابه
Small NFAs from Regular Expressions: Some Experimental Results
Regular expressions (REs), because of their succinctness and clear syntax, are the common choice to represent regular languages. However, efficient pattern matching or word recognition depend on the size of the equivalent nondeterministic finite automata (NFA). We present the implementation of several algorithms for constructing small ε-free NFAs from REs within the FAdo system, and a compariso...
متن کاملRegular Expressions and NFAs without ε-Transitions
We consider the problem of converting regular expressions into ε-free NFAs with as few transitions as possible. If the regular expression has length n and is defined over an alphabet of size k, then the previously best construction uses O(n ·min{k, log2 n}· log2 n) transitions. We show that O(n · log2 2k · log2 n) transitions suffice. For small alphabets, for instance if k = O(log2 log2 n), we ...
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A conservative extension to traditional nondeterministic finite automata is proposed to keep track of the positions in the input string for the last uses of selected transitions, by adding ”tags” to transitions. The resulting automata are reminiscent of nondeterministic Mealy machines. Formal semantics of automata with tagged transitions is given. An algorithm is given to convert these augmente...
متن کاملFrom Regular Expressions to Deterministic Automata
The main theorem allows an elegant algorithm to be refined into an efficient one. The elegant algorithm for constructing a finite automaton from a regular expression is based on 'derivatives of' regular expressions; the efficient algorithm is based on 'marking of' regular expressions. Derivatives of regular expressions correspond to state transitions in finite automata. When a finite automaton ...
متن کاملFrom $\mu$-Regular Expressions to Pushdown Automata
We extend Antimirov’s partial derivatives from regular expressions to μ-regular expressions that describe context-free languages. We prove the correctness of partial derivatives as well as the finiteness of the set of iterated partial derivatives. The latter are used as pushdown symbols in our construction of a nondeterministic pushdown automaton, which generalizes Antimirov’s NFA construction.
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 2011
ISSN: 0304-3975
DOI: 10.1016/j.tcs.2011.05.058