Computing the Threshold for q-Gram Filters
SWAT '02 Proceedings of the 8th Scandinavian Workshop on Algorithm Theory
Efficient algorithms for testing the twins property
Journal of Automata, Languages and Combinatorics - Special issue: Selected papers of the workshop weighted automata: Theory and applications (Dresden University of Technology (Germany), March 4-8, 2002)
Determinization of finite state weighted tree automata
Journal of Automata, Languages and Combinatorics
Deciding unambiguity and sequentiality from a finitely ambiguous max-plus automaton
Theoretical Computer Science - Developments in language theory
Efficient simulation of nondeterministic weighted finite automata
Journal of Automata, Languages and Combinatorics - Special issue: Selected papers of the fourth international workshop on descriptional complexity of formal systems
Theoretical Computer Science - In honour of Professor Christian Choffrut on the occasion of his 60th birthday
On the equivalence of weighted finite-state transducers
ACLdemo '04 Proceedings of the ACL 2004 on Interactive poster and demonstration sessions
Skew and infinitary formal power series
Theoretical Computer Science
Weighted tree automata and weighted logics
Theoretical Computer Science
Weighted automata and weighted logics
Theoretical Computer Science
Digital Images: Weighted Automata Theoretical Aspects
Proceedings of the 2005 conference on Advances in Logic Based Intelligent Systems: Selected Papers of LAPTEC 2005
Weighted automata and weighted logics with discounting
Theoretical Computer Science
Weighted finite automata over strong bimonoids
Information Sciences: an International Journal
Star normal form, rational expressions, and glushkov WFAs properties
CIAA'02 Proceedings of the 7th international conference on Implementation and application of automata
From Glushkov WFAs to rational expressions
DLT'03 Proceedings of the 7th international conference on Developments in language theory
Deciding the sequentiality of a finitely ambiguous max-plus automaton
DLT'03 Proceedings of the 7th international conference on Developments in language theory
Skew and infinitary formal power series
ICALP'03 Proceedings of the 30th international conference on Automata, languages and programming
An improved algorithm for determinization of weighted and fuzzy automata
Information Sciences: an International Journal
Weighted automata and weighted logics
ICALP'05 Proceedings of the 32nd international conference on Automata, Languages and Programming
Linear encoding scheme for weighted finite automata
CIAA'04 Proceedings of the 9th international conference on Implementation and Application of Automata
From Glushkov WFAs to \mathbb{K}-Expressions
Fundamenta Informaticae
Rigorous approximated determinization of weighted automata
Theoretical Computer Science
Trimming visibly pushdown automata
CIAA'13 Proceedings of the 18th international conference on Implementation and Application of Automata
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We study the problem of constructing the deterministic equivalent of a nondeterministic weighted finite-state automaton (WFA). Determinization of WFAs has important applications in automatic speech recognition (ASR). We provide the first polynomial-time algorithm to test for the twins property, which determines if a WFA admits a deterministic equivalent. We also give upper bounds on the size of the deterministic equivalent; the bound is tight in the case of acyclic WFAs. Previously, Mohri presented a superpolynomial-time algorithm to test for the twins property, and he also gave an algorithm to determinize WFAs. He showed that the latter runs in time linear in the size of the output when a deterministic equivalent exists; otherwise, it does not terminate. Our bounds imply an upper bound on the running time of this algorithm.Given that WFAs can expand exponentially in size when determinized, we explore why those that occur in ASR tend to shrink when determinized. According to ASR folklore, this phenomenon is attributable solely to the fact that ASR WFAs have simple topology, in particular, that they are acyclic and layered. We introduce a very simple class of WFAs with this structure, but we show that the expansion under determinization depends on the transition weights: some weightings cause them to shrink, while others, including random weightings, cause them to expand exponentially. We provide experimental evidence that ASR WFAs exhibit this weight dependence. That they shrink when determinized, therefore, is a result of favorable weightings in addition to special topology. These analyses and observations have been used to design a new, approximate WFA determinization algorithm, reported in a separate paper along with experimental results showing that it achieves significant WFA size reduction with negligible impact on ASR performance.