Abstract. An anticipatory system for guiding plot development in interactive narratives is described. The executable model is a finite automaton that provides the implemented system with a lookahead. The identification of undesirable future states in the model is used to guide the player, in a transparent manner. In this way, too radical twists of the plot that lead to behaviors of the autonomous fellow players, which may be experienced as counter-intuitive, can be avoided. Since the player participates in the development of the plot, such guidance can have many forms, depending on the environment of the player, on the behavior of the other players, and on the means of player interaction. We present a top-down design method for interactive narratives which make designs suitable for the implementation of anticipatory mechanisms. Use of the method is illustrated by application to our interactive computer game Kaktus. 1 Interactive Narrative

It has long been known that WS1S is decidable through the use of finite automata. However, since the worst case running time has been proven to grow extremely quickly, few have explored the implementation of the algorithm. In this paper we describe some of the points of interest that have come up while coding and running the algorithm. These points include the data structures used as well as the special properties of the automata, which we can exploit to perform minimization very quickly in certain cases. We also present some data that enable us to gain insight into how the algorithm performs in the average case, both on random inputs ans on inputs that come from the use of Presburger Arithmetic (which can be converted to WS1S) in compiler optimization. 1 Introduction 1.1 Definitions 1.1.1 WS1S The language L S1S is the second-order predicate calculus ranging over the natural numbers, with variables x 1 ; X 1 ; x 2 ; X 2 ; : : : (to represent numbers and sets of numbers), r...

. This paper describes a Prolog implementation of multi-tape finite-state automata and illustrates its use with a rewrite rules system. Operators which are multi-tape specific are defined and algorithms for constructing their behaviour into multi-tape machines are given. 1 Introduction Finite-state machines have been used in natural language and speech systems for a few decades (for the latest in the field, see (Roche, 1997)). Their ease of implementation and mathematical elegance made them popular for many purposes, especially systems which require regular rewrite rules. Traditionally, two versions of finite-state machines have been used: acceptors -- with one input tape -- where each transition is marked with a symbol, and transducers (or Mealy machines (Mealy, 1955)) -- with one input tape and one output tape -- where a transition is marked with two symbols for input and output, respectively. Hence, a transducer is seen as describing a mathematical set-theoretic binary relation. ...

Apart from the theoretical worst-case running time analysis not much is known about the average-case analysis or practical performance of finite automata minimization algorithms. On this paper we compare the running time of four minimization algorithms based on experimental results. We applied these algorithms to both deterministic and nondeterministic random automata.

In Natural Language Processing (NLP), research results from software engineering and software technology have often been neglected.

We present a new taxonomy and toolkit of keyword pattern matching algorithms. The new taxonomy is an extension of a prior taxonomy of such algorithms. It includes a number of algorithms (including factor- and factor oracle-based and bit-parallel prefix-based pattern matching algorithms) that have been published or received a lot of attention in the last decade. Based on the new taxonomy, we developed a pattern matching toolkit. This toolkit is a revision and extension of the SPARE Parts toolkit that had been developed based on the original taxonomy. We present the architecture of the new toolkit, which is named SPARE Time. Samenvatting We presenteren een nieuwe taxonomie en toolkit van algorithmen voor keyword pattern matching. De nieuwe taxonomie vormt een uitbreiding van een eerdere taxonomie van zulke algorithmen. Ze bevat een aantal algorithmen (waaronder algorithmen gebaseerd op factoren en factor oracles en bit-parallelle algorithmen gebaseerd op prefixen) die in de afgelopen tien jaar gepubliceerd zijn of veel aandacht gekregen hebben.

this paper, we present a taxonomy of algorithms for constructing minimal acyclic deterministic finite automata (MADFAs). MADFAs represent finite languages and are therefore useful in applications such as storing words for spellchecking, computer and biological virus searching, text indexing and XML tag lookup. In such applications, the automata can grow extremely large (with more than 10

We present a solution to the problem of regular expression searching on compressed text. The format we choose is the Ziv-Lempel family, specifically the LZ78 and LZW variants. Given a text of length u compressed into length n, and a pattern of length m, we report all the R occurrences of the pattern in the text in O(2 m +mn+Rm log m) worst case time. On average this drops to O(m 2

This paper presents a new taxonomy of sublinear (multiple) keyword pattern matching algorithms. Based on an earlier taxonomy by Watson and Zwaan [WZ96, WZ95], this new taxonomy includes not only suffix-based algorithms related to the Boyer-Moore, Commentz-Walter and Fan-Su algorithms, but factor- and factor oracle-based algorithms such as Backward DAWG Matching and Backward Oracle Matching as well. In particular, we show how suffix-based (Commentz-Walter like), factor- and factor oracle-based sublinear keyword pattern matching algorithms can all be seen as instantiations of a general sublinear algorithm skeleton. In addition, we show all shift functions defined for the suffix-based algorithms to be in principle reusable for factor- and factor oracle-based algorithms. The taxonomy is based on deriving the algorithms from a common starting point by adding algorithm and problem details, in order to arrive at efficient or well-known algorithms. Such a presentation provides correctness arguments for the algorithms as well as clarity on how the algorithms are related

Abstract—We introduce bisimulation up to congruence as a technique for proving language equivalence of non-deterministic finite automata. Exploiting this technique, we devise an optimisation of the classical algorithm by Hopcroft and Karp [12] that, instead of computing the whole determinised automata, explores only a small portion of it. Although the optimised algorithm remains exponential in worst case (the problem is PSPACEcomplete), experimental results show improvements of several orders of magnitude over the standard algorithm. I.