Showing papers on "Deterministic pushdown automaton published in 2003"

Stream processing of XPath queries with predicates

Abstract: We consider the problem of evaluating large numbers of XPath filters, each with many predicates, on a stream of XML documents. The solution we propose is to lazily construct a single deterministic pushdown automata, called the XPush Machine from the given XPath fllters. We describe a number of optimization techniques to make the lazy XPush machine more efficient, both in terms of space and time. The combination of these optimizations results in high, sustained throughput. For example, if the total number of atomic predicates in the filters is up to 200000, then the throughput is at least 0.5 MB/sec: it increases to 4.5 MB/sec when each fllter contains a single predicate.

Automata, languages and programming : 30th International Colloquium, ICALP 2003, Eindhoven, the Netherlands, June 30-July 4, 2003 : proceedings

Abstract: Invited Lectures.- Polarized Process Algebra and Program Equivalence.- Problems on RNA Secondary Structure Prediction and Design.- Some Issues Regarding Search, Censorship, and Anonymity in Peer to Peer Networks.- The SPQR-Tree Data Structure in Graph Drawing.- Model Checking and Testing Combined.- Logic and Automata: A Match Made in Heaven.- Algorithms.- Pushdown Automata and Multicounter Machines, a Comparison of Computation Modes.- Generalized Framework for Selectors with Applications in Optimal Group Testing.- Decoding of Interleaved Reed Solomon Codes over Noisy Data.- Process Algebra.- On the Axiomatizability of Ready Traces, Ready Simulation, and Failure Traces.- Resource Access and Mobility Control with Dynamic Privileges Acquisition.- Replication vs. Recursive Definitions in Channel Based Calculi.- Approximation Algorithms.- Improved Combinatorial Approximation Algorithms for the k-Level Facility Location Problem.- An Improved Approximation Algorithm for the Asymmetric TSP with Strengthened Triangle Inequality.- An Improved Approximation Algorithm for Vertex Cover with Hard Capacities.- Approximation Schemes for Degree-Restricted MST and Red-Blue Separation Problem.- Approximating Steiner k-Cuts.- MAX k-CUT and Approximating the Chromatic Number of Random Graphs.- Approximation Algorithm for Directed Telephone Multicast Problem.- Languages and Programming.- Mixin Modules and Computational Effects.- Decision Problems for Language Equations with Boolean Operations.- Generalized Rewrite Theories.- Complexity.- Sophistication Revisited.- Scaled Dimension and Nonuniform Complexity.- Quantum Search on Bounded-Error Inputs.- A Direct Sum Theorem in Communication Complexity via Message Compression.- Data Structures.- Optimal Cache-Oblivious Implicit Dictionaries.- The Cell Probe Complexity of Succinct Data Structures.- Succinct Representations of Permutations.- Succinct Dynamic Dictionaries and Trees.- Graph Algorithms.- Labeling Schemes for Weighted Dynamic Trees.- A Simple Linear Time Algorithm for Computing a (2k - 1)-Spanner of O(n 1+1/k ) Size in Weighted Graphs.- Multicommodity Flows over Time: Efficient Algorithms and Complexity.- Multicommodity Demand Flow in a Tree.- Automata.- Skew and Infinitary Formal Power Series.- Nondeterminism versus Determinism for Two-Way Finite Automata: Generalizations of Sipser's Separation.- Residual Languages and Probabilistic Automata.- A Testing Scenario for Probabilistic Automata.- The Equivalence Problem for t-Turn DPDA Is Co-NP.- Flip-Pushdown Automata: k + 1 Pushdown Reversals Are Better than k.- Optimization and Games.- Convergence Time to Nash Equilibria.- Nashification and the Coordination Ratio for a Selfish Routing Game.- Stable Marriages with Multiple Partners: Efficient Search for an Optimal Solution.- An Intersection Inequality for Discrete Distributions and Related Generation Problems.- Graphs and Bisimulation.- Higher Order Pushdown Automata, the Caucal Hierarchy of Graphs and Parity Games.- Undecidability of Weak Bisimulation Equivalence for 1-Counter Processes.- Bisimulation Proof Methods for Mobile Ambients.- On Equivalent Representations of Infinite Structures.- Online Problems.- Adaptive Raising Strategies Optimizing Relative Efficiency.- A Competitive Algorithm for the General 2-Server Problem.- On the Competitive Ratio for Online Facility Location.- A Study of Integrated Document and Connection Caching.- Verification.- A Solvable Class of Quadratic Diophantine Equations with Applications to Verification of Infinite-State Systems.- Monadic Second-Order Logics with Cardinalities.- ? 2 ? ? 2 ? AFMC.- Upper Bounds for a Theory of Queues.- Around the Internet.- Degree Distribution of the FKP Network Model.- Similarity Matrices for Pairs of Graphs.- Algorithmic Aspects of Bandwidth Trading.- Temporal Logic and Model Checking.- CTL+ Is Complete for Double Exponential Time.- Hierarchical and Recursive State Machines with Context-Dependent Properties.- Oracle Circuits for Branching-Time Model Checking.- Graph Problems.- There Are Spanning Spiders in Dense Graphs (and We Know How to Find Them).- The Computational Complexity of the Role Assignment Problem.- Fixed-Parameter Algorithms for the (k, r)-Center in Planar Graphs and Map Graphs.- Genus Characterizes the Complexity of Graph Problems: Some Tight Results.- Logic and Lambda-Calculus.- The Definition of a Temporal Clock Operator.- Minimal Classical Logic and Control Operators.- Counterexample-Guided Control.- Axiomatic Criteria for Quotients and Subobjects for Higher-Order Data Types.- Data Structures and Algorithms.- Efficient Pebbling for List Traversal Synopses.- Function Matching: Algorithms, Applications, and a Lower Bound.- Simple Linear Work Suffix Array Construction.- Types and Categories.- Expansion Postponement via Cut Elimination in Sequent Calculi for Pure Type Systems.- Secrecy in Untrusted Networks.- Locally Commutative Categories.- Probabilistic Systems.- Semi-pullbacks and Bisimulations in Categories of Stochastic Relations.- Quantitative Analysis of Probabilistic Lossy Channel Systems.- Discounting the Future in Systems Theory.- Information Flow in Concurrent Games.- Sampling and Randomness.- Impact of Local Topological Information on Random Walks on Finite Graphs.- Analysis of a Simple Evolutionary Algorithm for Minimization in Euclidean Spaces.- Optimal Coding and Sampling of Triangulations.- Generating Labeled Planar Graphs Uniformly at Random.- Scheduling.- Online Load Balancing Made Simple: Greedy Strikes Back.- Real-Time Scheduling with a Budget.- Improved Approximation Algorithms for Minimum-Space Advertisement Scheduling.- Anycasting in Adversarial Systems: Routing and Admission Control.- Geometric Problems.- Dynamic Algorithms for Approximating Interdistances.- Solving the Robots Gathering Problem.

A gap property of deterministic tree languages

Abstract: We show that a tree language recognized by a deterministic parity automaton is either hard for the co-Buchi level and therefore cannot be recognized by a weak alternating automaton, or is on a very low level in the hierarchy of weak alternating automata. A topological counterpart of this property is that a deterministic tree language is either Π11 complete (and hence nonBorel), or it is on the level Π30 of the Borel hierarchy. We also give a new simple proof of the strictness of the hierarchy of weak alternating automata.

Flip-pushdown automata: k + 1 pushdown reversals are better than k

Abstract: Flip-pushdown automata are pushdown automata with the additional power to flip or reverse its pushdown, and were recently introduced by Sarkar [13]. We solve most of Sarkar's open problems. In particular, we show that k+1 pushdown reversals are better than k for both deterministic and nondeterministic flip-pushdown automata, i.e., there are languages which can be recognized by a deterministic flip-pushdown automaton with k+1 pushdown reversals but which cannot be recognized by a k-flip-pushdown (deterministic or nondeterministic). Furthermore, we investigate closure and non-closure properties as well as computational complexity problems such as fixed and general membership.

Games on pushdown graphs and extensions

Abstract: Two player games are a standard model of reactive computation, where e.g. one player is the controller and the other is the environment. A game is won by a player if she has a winning strategy, i.e., if she can win every play. Given a finite description of the game, our aim is to compute the winner and a winning strategy. For finite graphs these problems have been solved for a long time, although some complexity questions remain open. We consider several classes of infinite graphs, from transition graphs of pushdown automata up to graphs of the Caucal hierarchy, and we investigate different winning conditions: reachability, recurrence (Büchi), parity, and the a called Σ3-condition. Two kinds of techniques are developed: a symbolic approach based on finite automata recognizing infinite sets of configurations and a game simulation which reduces a given game into a simpler one and solves it. Different kinds of strategies are also constructed: either positional or based on pushdown stack memories.

The equivalence problem for t-turn dpda is co-NP

Abstract: We introduce new tools allowing to deal with the equality-problem for prefix-free languages. We illustrate our ideas by showing that, for every fixed integer t ≥ 1, the equivalence problem for t-turn deterministic pushdown automata is co-NP. This complexity result refines those of [Val74, Bee76].

Flip-pushdown automata: Nondeterminism is better than determinism

Abstract: Flip-pushdown automata are pushdown automata with the additional ability to flip or reverse its pushdown. We investigate deterministic and nondeterministic flip-pushdown automata accepting by final state or empty pushdown. In particular, for nondeterministic flip-pushdown automata both acceptance criterion are equally powerful, while for determinism, acceptance by empty pushdown is strictly weaker. This nicely fits into the well-known results on ordinary pushdown automata. Moreover, we consider hierarchies of flip-pushdown automata w.r.t. the number of pushdown reversals. There we show that nondeterminism is better than determinism. Moreover, since there are languages which can be recognized by a deterministic flip-pushdown automaton with k + 1 pushdown reversals but which cannot be recognized by a k-flip-pushdown (deterministic or nondeterministic) as shown in [9] we are able to complete our investigations with incomparabiiity results on different levels of the hierarchies under consideration.

Deciding co-observability is PSPACE-complete

Abstract: In this note, we reduce the deterministic finite-state automata intersection problem to the problem of deciding co-observability for regular languages using a polynomial-time many-one mapping. This demonstrates that the problem of deciding co-observability for languages marked by deterministic finite-state automata is PSPACE-complete. We use a similar reduction to reduce the deterministic finite-state automata intersection problem to deciding other versions of co-observability introduced in a previous paper. These results imply that the co-observability of regular languages most likely cannot be decided in polynomial time unless we make further restrictions on the languages. These results also show that deciding decentralized supervisor existence is PSPACE-complete and therefore probably intractable.

Flip-pushdown automata: nondeterminism is better than determinism

Abstract: Flip-pushdown automata are pushdown automata with the additional ability to flip or reverse its pushdown We investigate deterministic and nondeterministic flip-pushdown automata accepting by final state or empty pushdown In particular, for nondeterministic flip-pushdown automata both acceptance criterion are equally powerful, while for determinism, acceptance by empty pushdown is strictly weaker This nicely fits into the well-known results on ordinary pushdown automata Moreover, we consider hierarchies of flip-pushdown automata wrt the number of pushdown reversals There we show that nondeterminism is better than determinism Moreover, since there are languages which can be recognized by a deterministic flip-pushdown automaton with k + 1 pushdown reversals but which cannot be recognized by a k-flip-pushdown (deterministic or nondeterministic) as shown in [9] we are able to complete our investigations with incomparability results on different levels of the hierarchies under consideration

Bideterministic automata and minimal representations of regular languages

Abstract: Bideterministic automata are deterministic automata with the property of their reversal automata also being deterministic. It has been known that a bideterministic automaton is the minimal deterministic automaton accepting its language. This paper shows that any bideterministic automaton is the unique minimal automaton among all (including nondeterministic) automata accepting the same language. We also present a more general result that shows that under certain conditions a minimal deterministic automaton accepting some language or the reversal of the minimal deterministic automaton of the reversal language is a minimal automaton representation of the language. These conditions can be checked in polynomial time.

Distributed pushdown automata systems: Computational power

Abstract: We introduce distributed pushdown automata systems consisting of several pushdown automata which work in turn on the input string placed on a common one-way input tape. The work of the components is based on protocols and strategies similar to those that cooperating distributed grammar systems use. We investigate the computational power of these mechanisms under different protocols for activating components and two ways of accepting the input string: with empty stacks or with final states which means that all components have empty stacks or are in final states, respectively, when the input string was completely read.

Pushdown automata and multicounter machines, a comparison of computation modes

Abstract: There are non-context-free languages which are recognizable by randomized pushdown automata even with arbitrarily small error probability. We give an example of a context-free language which cannot be recognized by a randomized pda with error probability smaller than 1/2 - O(log2 n/n) for input size n. Hence nondeterminism can be stronger than probabilism with weakly-unbounded error. Moreover, we construct two deterministic context-free languages whose union cannot be accepted with error probability smaller than 1/3-2-Ω(n), where n is the input length. Since the union of any two deterministic context-free languages can be accepted with error probability 1/3, this shows that 1/3 is a sharp threshold and hence randomized pushdown automata do not have amplification. One-way two-counter machines represent a universal model of computation. Here we consider the polynomial-time classes of multicounter machines with a constant number of reversals and separate the computational power of nondeterminism, randomization and determinism.

Some variants in communication of parallel communicating pushdown automata

Abstract: We consider automata systems consisting of several pushdown automata working in parallel and communicating the contents of their stacks by request. We show that centralized non-returning parallel communicating pushdown automata systems with three components recognize all recursively enumerable languages. We also show that centralized returning pushdown automata systems accept non-ET0L languages. We study two variants of communication: one uses filters in communication and in the other only specified number of symbols are communicated. We prove that all these systems accept the family of recursively enumerable languages both in the centralized and in the non-centralized strategies and in both returning and non-returning communication modes with only two components.

On The Space Complexity Of Turn Bounded Pushdown Automata

Abstract: A pushdown automaton is said to make a turn at a given instant if it changes at that instant from stack increasing to stack decreasing. Let \hbox{NPDA-TURN}(\,f(n)) and \hbox{DPDA-TURN}(\,f(n)) denote the classes of languages accepted by nondeterministic and deterministic pushdown automata respectively that make at most f v ( n ) turns for any input of length n . In this paper the following inclusions that express the space complexity of turn bounded pushdown automata are given: \hbox{DPDA-TURN}(\,f(n)) \subseteq {\bf DSPACE}(\log f(n)\log n) , and \hbox{NPDA-TURN}(\,f(n)) \subseteq {\bf NSPACE} (\log f(n)\log n) . In particular, it follows that finite-turn pushdown automata are logarithmic space bounded: \hbox{DPDA-TURN}(O(1))\subseteq {\bf DL} and \hbox{NPDA-TURN}(O(1))\subseteq {\bf NL} , from which two corollaries follow: one is that the class of metalinear context-free languages is complete for NL , and the other is that a more tight inclusion \hbox{NPDA-TURN}(\,f(n)) \subseteq {\bf DSPACE}(\log^2 f(...

Distributed pushdown automata systems: computational power

Abstract: We introduce distributed pushdown automata systems consisting of several pushdown automata which work in turn on the input string placed on a common one-way input tape The work of the components is based on protocols and strategies similar to those that cooperating distributed grammar systems use We investigate the computational power of these mechanisms under different protocols for activating components and two ways of accepting the input string: with empty stacks or with final states which means that all components have empty stacks or are in final states, respectively, when the input string was completely read

An Extension of Pushdown System and Its Model Checking Method

Abstract: In this paper, we present a class of infinite transition systems which is an extension of pushdown systems (PDS), and show that LTL (linear temporal logic) model checking for the class is decidable. Since the class is defined as a subclass of term rewriting systems, pushdown stack of PDS is naturally extended to tree structure. By this extension, we can model recursive programs with exception handling.

Alphabetic pushdown tree transducers

Abstract: We introduce the concept of an alphabetic pushdown tree transducer, by adding a stack to an alphabetic tree transducer in the same way as a pushdown tree automaton is obtained from a top-down tree automaton. The stack of the general model contains trees, however, we also consider a restricted model of which the stack contains only unary trees. We give a characterization of the tree transformation induced by a restricted alphabetic pushdown tree transducer in terms of an algebraic forest over a suitable ranked alphabet and a bimorphism. We compare the class of tree relations induced by the alphabetic pushdown tree transducers with known classes of tree transformations. Finally, a new hierarchy of tree relations is established.

Equivalence of real‐time DPDAs and discrete extended simple recurrent networks with some restrictions

Abstract: To model human natural language processing using computation theory, Elman proposed a simple recurrent network. A simple recurrent network is a recurrent neural network with restrictions added to the connections between gates. When the range of the function for computing each gate of a simple recurrent network is a finite set (this is called a discrete simple recurrent network), its computational capability is known to be equivalent to that of a finite automaton with output. This paper introduces a modification of a discrete simple recurrent network so that it has a computational capability equivalent to that of a real-time deterministic pushdown automaton (real-time DPDA). In other words, the discrete simple recurrent network is extended as follows. (1) It contains a number of gates equal to a constant multiple of the input length, and (2) those gates can be used to simulate a stack with a depth of at most the input length. © 2003 Wiley Periodicals, Inc. Syst Comp Jpn, 34(7): 55–62, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10275

One-sided error quantum pushdown automata with classical stack operations

Abstract: One of important questions on quantum computing is whether there is a computational gap between the models that are allowed to use quantum effects and the models that are not. Several types of quantum computation models have been proposed, including quantum finite automata and quantum pushdown automata (with quantum pushdown stack). It has been shown that some quantum computation models are more powerful than classical counterparts and some are not since quantum computation models are required to obey some restrictions such as reversible state transitions. In this paper, we investigate the power of quantum pushdown automata whose stack is assumed to be implemented as a classical device, and show that they are strictly more powerful than classical counterparts in the one-sided error setting. That is, we show that there is a non-context-free language which quantum pushdown automata with classical stack operations can recognize with one-sided error.

Alphabetic pushdown tree transducers

Abstract: We introduce the concept of an alphabetic pushdown tree transducer, by adding a stack to an alphabetic tree transducer in the same way as a pushdown tree automaton is obtained from a top-down tree automaton. The stack of the general model contains trees, however, we also consider a restricted model of which the stack contains only unary trees. We give a characterization of the tree transformation induced by a restricted alphabetic pushdown tree transducer in terms of an algebraic forest over a suitable ranked alphabet and a bimorphism.We compare the class of tree relations induced by the alphabetic pushdown tree transducers with known classes of tree transformations. Finally, a new hierarchy of tree relations is established.