منابع مشابه
Branching Pushdown Tree Automata
We observe that pushdown tree automata (PTAs) known in the literature cannot express combinations of branching and pushdown properties. This is because a PTA processes the children of a tree node in possibly different control states but with identical stacks. We propose branching pushdown tree automata (BPTAs) as a solution. In a BPTA, a push-move views its matching pops as an unbounded, unorde...
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A new kind of an acyclic pushdown automaton for an ordered tree is presented. The nonlinear tree pattern pushdown automaton represents a complete index of the tree for nonlinear tree patterns and accepts all nonlinear tree patterns which match the tree. Given a tree with n nodes, the number of such nonlinear tree patterns is O((2+ v)n), where v is the number of variables in the patterns. We dis...
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Dynamic Pushdown Networks (DPNs) are an abstract model for concurrent programs with recursive procedures and dynamic process creation. Usually, DPNs are described with an interleaving semantics, where an execution is a sequence of steps. Recently, we introduced a true-concurrency semantics for DPNs, where executions are trees. The standard analysis methods for DPNs are based on a saturation alg...
متن کاملPushdown Automata
Families of Languages AFL thm if F is closed under substitution with λ-free regular sets, morphism, union with regular sets [easy for cfg] & intersection with regular sets, then F is closed under inverse morphism Figure 26: closure properties of CF II 12 intersection with regular languages a;A/α a a;A/α λ;A/α λ;A/α { } } { ⇒ ⇒ { anbn | n ≥ 1 }∗ ∩ { w ∈ {a, b}∗ |#ax even } r1 p1 q1 r0 p0 q0 r p ...
متن کاملTree Indexing by Pushdown Automata and Repeats of Subtrees
We consider the problem of finding all subtree repeats in a given unranked ordered tree. We show a new, elegant, and simple method, which is based on the construction of a tree indexing structure called the subtree pushdown automaton. We propose a solution for computing all subtree repeats from the deterministic subtree pushdown automaton constructed over the subject tree. The method we present...
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ژورنال
عنوان ژورنال: Journal of Computer and System Sciences
سال: 1985
ISSN: 0022-0000
DOI: 10.1016/0022-0000(85)90002-9