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21
Modality in Dialogue: Planning, Pragmatics and Computation
, 1998
"... Natural language generation (NLG) is first and foremost a reasoning task. In this reasoning, a system plans a communicative act that will signal key facts about the domain to the hearer. In generating action descriptions, this reasoning draws on characterizations both of the causal properties of the ..."
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Cited by 37 (9 self)
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Natural language generation (NLG) is first and foremost a reasoning task. In this reasoning, a system plans a communicative act that will signal key facts about the domain to the hearer. In generating action descriptions, this reasoning draws on characterizations both of the causal properties of the domain and the states of knowledge of the participants in the conversation. This dissertation shows how such characterizations can be specified declaratively and accessed efficiently in NLG. The heart of this dissertation is a study of logical statements about knowledge and action in modal logic. By investigating the prooftheory of modal logic from a logic programming point of view, I show how many kinds of modal statements can be seen as straightforward instructions for computationally manageable search, just as Prolog clauses can. These modal statements provide sufficient expressive resources for an NLG system to represent the effects of actions in the world or to model an addressee whose knowledge in some respects exceeds and in other respects falls short of its own. To illustrate the use of such statements, I describe how the SPUD sentence planner exploits a modal knowledge base to
On Equality Upto Constraints over Finite Trees, Context Unification, and OneStep Rewriting
"... We introduce equality upto constraints over finite trees and investigate their expressiveness. Equality upto constraints subsume equality constraints, subtree constraints, and onestep rewriting constraints. ..."
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Cited by 27 (7 self)
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We introduce equality upto constraints over finite trees and investigate their expressiveness. Equality upto constraints subsume equality constraints, subtree constraints, and onestep rewriting constraints.
Unification with Sequence Variables And Flexible Arity Symbols and its Extension with PatternTerms
 ARTIFICIAL INTELLIGENCE, AUTOMATED REASONING AND SYMBOLIC COMPUTATION. PROC. OF JOINT AISC’2002 – CALCULEMUS’2002 CONFERENCE, VOLUME 2385 OF LNAI
, 2002
"... A minimal and complete unification procedure for a theory with individual and sequence variables, free constants and free fixed and flexible arity function symbols is described and a brief overview of an extension with patternterms is given. ..."
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Cited by 27 (14 self)
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A minimal and complete unification procedure for a theory with individual and sequence variables, free constants and free fixed and flexible arity function symbols is described and a brief overview of an extension with patternterms is given.
Solvability of context equations with two context variables is decidable
 THE JOURNAL OF SYMBOLIC COMPUTATION
, 1999
"... Context unification is a natural variant of second order unification that represents a generalization of word unification at the same time. While second order unification is wellknown to be undecidable and word unification is decidable it is currently open if solvability of context equations is deci ..."
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Cited by 26 (2 self)
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Context unification is a natural variant of second order unification that represents a generalization of word unification at the same time. While second order unification is wellknown to be undecidable and word unification is decidable it is currently open if solvability of context equations is decidable. We show that solvability of systems of context equations with two context variables is decidable. The context variables may have an arbitrary number of occurrences, and the equations may contain an arbitrary number of individual variables as well. The result holds under the assumption that the first order background signature is finite.
CLP(Flex): Constraint Logic Programming Applied to XML Processing
 On the Move to Meaningful Internet Systems 2004: CoopIS, DOA, and ODBASE. Proc. of Confederated Int. Conferences, volume 3291 of LNCS
, 2004
"... In this paper we present an implementation of a constraint solving module, CLP(Flex), for dealing with unification in an equality theory for terms with flexible arity function symbols. ..."
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Cited by 21 (10 self)
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In this paper we present an implementation of a constraint solving module, CLP(Flex), for dealing with unification in an equality theory for terms with flexible arity function symbols.
Dominance Constraints in Context Unification
, 1998
"... Tree descriptions based on dominance constraints are popular in several areas of computational linguistics including syntax, semantics, and discourse. Tree descriptions in the language of context unification have attracted some interest in unification and rewriting theory. Recently, dominance constr ..."
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Cited by 14 (10 self)
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Tree descriptions based on dominance constraints are popular in several areas of computational linguistics including syntax, semantics, and discourse. Tree descriptions in the language of context unification have attracted some interest in unification and rewriting theory. Recently, dominance constraints and context unification have both been used in different underspecified approaches to the semantics of scope, parallelism, and their interaction. This raises the question whether both description languages are related. In this paper, we show for a first time that dominance constraints can be expressed in context unification. We also prove that dominance constraints extended with parallelism constraints are equal in expressive power to context unification.
Satisfiability of Word Equations with Constants is in Exponential Space
, 1998
"... In this paper we study solvability of equations over free semigroups, known as word equations, particularly Makanin's algorithm, a general procedure to decide if a word equation has a solution. The upper bound timecomplexity of Makanin's original decision procedure (1977) was quadruple ex ..."
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Cited by 13 (3 self)
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In this paper we study solvability of equations over free semigroups, known as word equations, particularly Makanin's algorithm, a general procedure to decide if a word equation has a solution. The upper bound timecomplexity of Makanin's original decision procedure (1977) was quadruple exponential in the length of the equation, as shown by Jaffar. In 1990 Ko'scielski and Pacholski reduced it to triple exponential, and conjectured that it could be brought down to double exponential. The present paper proves this conjecture. In fact we prove the stronger fact that its spacecomplexity is single exponential. Introduction Solving equations in equationally defined free algebras (Unification) is a widely used technique in Computer Science, see e.g. [3]. In particular, solving equations in free semigroups, i.e. word equations, is of great interest in e.g. associative rewriting and completion, string unification in PROLOG3, extensions of string rewrite systems, unification in some theories...
Typebased {XML} Processing in Logic Programming
 In PADL 2003
, 2003
"... In this paper we propose a typebased framework for using logic programming for XML processing. We transform XML documents into terms and DTDs into regular types. We implemented a standard type inference algorithm for logic programs and use the types corresponding to the DTDs as additional type ..."
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Cited by 13 (2 self)
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In this paper we propose a typebased framework for using logic programming for XML processing. We transform XML documents into terms and DTDs into regular types. We implemented a standard type inference algorithm for logic programs and use the types corresponding to the DTDs as additional type declarations for logic programs for XML processing. Due to the correctness of the type inference this makes it possible to use logic programs as an implicitly typed processing language for XML with static type (in this case DTDs) validation. As far as we know this is the first work adding type validation at compile time to the use of logic programming for XML processing.
Solving equations with sequence variables and sequence functions
 J. Symbolic Computation
, 2007
"... Term equations involving individual and sequence variables and sequence function symbols are studied. Function symbols can have either fixed or flexible arity. A sequence variable can be instantiated by any finite sequence of terms. A sequence function abbreviates a finite sequence of functions all ..."
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Cited by 11 (8 self)
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Term equations involving individual and sequence variables and sequence function symbols are studied. Function symbols can have either fixed or flexible arity. A sequence variable can be instantiated by any finite sequence of terms. A sequence function abbreviates a finite sequence of functions all having the same argument lists. It is proved that solvability of systems of equations of this form is decidable. A new unification procedure that enumerates a complete almost minimal set of solutions is presented, together with variations for special cases. The procedure terminates if the solution set is finite. Applications in various areas of artificial intelligence, symbolic computation, and programming are discussed. 1