We show that for several classes of idempotent semirings the least fixed-point of a polynomial system of equations X = f(X) is equal to the least fixed-point of a linear system obtained by "linearizing" the polynomials of in a certain way. Our proofs rely on derivation tree analysis, a proof principle that combines methods from algebra, calculus, and formal language theory, and was first used in [5] to show that Newton's method over commutative and idempotent semirings converges in a linear number of steps. Our results lead to efficient generic algorithms for computing the least fixed-point. We use these algorithms to derive several consequences, including an O(N 3) algorithm for computing the throughput of a context-free grammar (obtained by speeding up the O(N 4) algorithm of [2]), and a generalization of Courcelle's result stating that the downward-closed image of a context-free language is regular [3]. © 2008 Springer-Verlag Berlin Heidelberg.
CITATION STYLE
Esparza, J., Kiefer, S., & Luttenberger, M. (2008). Derivation tree analysis for accelerated fixed-point computation. In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Vol. 5257 LNCS, pp. 301–313). https://doi.org/10.1007/978-3-540-85780-8_24
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