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On the Determinization of Weighted Automata
 Journal of Automata, Languages and Combinatorics
, 2005
"... In the paper, we generalize an algorithm and some related results by Mohri [25] for determinization of weighted finite automata (WFA) over the tropical semiring. We present the underlying mathematical concepts of his algorithm in a precise way for arbitrary semirings. We define a class of semirings ..."
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In the paper, we generalize an algorithm and some related results by Mohri [25] for determinization of weighted finite automata (WFA) over the tropical semiring. We present the underlying mathematical concepts of his algorithm in a precise way for arbitrary semirings. We define a class of semirings in which we can show that the twins property is sufficient for the termination of the algorithm. We also introduce singlevalued WFA and give a partial correction of a claim by Mohri [25] by showing several characterizations of singlevalued WFA, e.g., the formal power series computed by a singlevalued WFA is subsequential iff it has bounded variation. Also, it is decidable in polynomial time whether a given WFA over the tropical semiring is singlevalued. 1
Strong Lexicalization of Tree Adjoining Grammars
"... Recently, it was shown (KUHLMANN, SATTA: Treeadjoining grammars are not closed under strong lexicalization. Comput. Linguist., 2012) that finitely ambiguous tree adjoining grammars cannot be transformed into a normal form (preserving the generated tree language), in which each production contains a ..."
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Recently, it was shown (KUHLMANN, SATTA: Treeadjoining grammars are not closed under strong lexicalization. Comput. Linguist., 2012) that finitely ambiguous tree adjoining grammars cannot be transformed into a normal form (preserving the generated tree language), in which each production contains a lexical symbol. A more powerful model, the simple contextfree tree grammar, admits such a normal form. It can be effectively constructed and the maximal rank of the nonterminals only increases by 1. Thus, simple contextfree tree grammars strongly lexicalize tree adjoining grammars and themselves. 1
DECIDING UNAMBIGUITY AND SEQUENTIALITY OF POLYNOMIALLY AMBIGUOUS MINPLUS AUTOMATA
, 2009
"... This paper solves the unambiguity and the sequentiality problem for polynomially ambiguous minplus automata. This result is proved through a decidable algebraic characterization involving socalled metatransitions and an application of results from the structure theory of finite semigroups. It is n ..."
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This paper solves the unambiguity and the sequentiality problem for polynomially ambiguous minplus automata. This result is proved through a decidable algebraic characterization involving socalled metatransitions and an application of results from the structure theory of finite semigroups. It is noteworthy that the equivalence problem is known to be undecidable for polynomially ambiguous automata.
Series which are both maxplus and minplus rational are unambiguous
 RAIRO  Theoretical Informatics and Applications 40
, 2006
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Sequential? Sylvain Lombardy a, Jacques Sakarovitch b
"... This paper is a survey where we try to organise the known answers to the question whether a given finite automaton with multiplicity in a semiring K is equivalent to a sequential, or input deterministic, one. We shall see that depending on K, the question goes from obvious to open, that the answer g ..."
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This paper is a survey where we try to organise the known answers to the question whether a given finite automaton with multiplicity in a semiring K is equivalent to a sequential, or input deterministic, one. We shall see that depending on K, the question goes from obvious to open, that the answer goes from yes to undecidable. We review results on sequentiality in the cases of series of finite image, of series with multiplicity in fields, and of series with multiplicity in idempotent semirings.
3.2 An Example of a Polynomially Ambiguous WFA.................... 4
, 2008
"... We show that the termination of Mohri’s algorithm is decidable for polynomially ambiguous weighted finite automata over the tropical semiring which gives a partial answer to a question by Mohri [29]. The proof relies on an improvement of the notion of the twins property and a Burnside type character ..."
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We show that the termination of Mohri’s algorithm is decidable for polynomially ambiguous weighted finite automata over the tropical semiring which gives a partial answer to a question by Mohri [29]. The proof relies on an improvement of the notion of the twins property and a Burnside type characterization for the finiteness of the set of states produced by Mohri’s algorithm. ∗ An extended abstract was presented at Journées Montoises d’Informatique Théorique 2006.
Residuation of tropical series: rationality issues
"... appor t de r ech er ch e ..."
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