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SPASS Version 3.5
 In Proc. Int’l Conf. Automated Deduction (CADE
, 2009
"... Abstract. SPASS is an automated theorem prover for full firstorder logic with equality and a number of nonclassical logics. This system description provides an overview of our recent developments in SPASS 3.5 including subterm contextual rewriting, improved split backtracking, a significantly fast ..."
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Cited by 34 (3 self)
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Abstract. SPASS is an automated theorem prover for full firstorder logic with equality and a number of nonclassical logics. This system description provides an overview of our recent developments in SPASS 3.5 including subterm contextual rewriting, improved split backtracking, a significantly faster FLOTTER implementation with additional control flags, completely symmetric implementation of forward and backward redundancy criteria, faster parsing with improved support for big files, faster and extended sort module, and support for include commands in input files. Finally, SPASS 3.5 can now parse files in TPTP syntax, comes with a new converter tptp2dfg and is distributed under a BSD style license. 1
The attentional blink provides episodic distinctiveness: Sparing at a cost
 Journal of Experimental Psychology: Human Perception and Performance
, 2009
"... The attentional blink (J. E. Raymond, K. L. Shapiro, & K. M. Arnell, 1992) refers to an apparent gap in perception observed when a second target follows a first within several hundred milliseconds. Theoretical and computational work have provided explanations for early sets of blink data, but m ..."
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Cited by 19 (3 self)
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The attentional blink (J. E. Raymond, K. L. Shapiro, & K. M. Arnell, 1992) refers to an apparent gap in perception observed when a second target follows a first within several hundred milliseconds. Theoretical and computational work have provided explanations for early sets of blink data, but more recent data have challenged these accounts by showing that the blink is attenuated when subjects encode strings of
Decision Problems in Ordered Rewriting
 In 13th IEEE Symposium on Logic in Computer Science (LICS
, 1997
"... A term rewrite system (TRS) terminates iff its rules are contained in a reduction ordering ?. In order to deal with any set of equations, including inherently nonterminating ones (like commutativity), TRS have been generalised to ordered TRS (E; ?), where equations of E are applied in whatever dir ..."
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Cited by 16 (7 self)
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A term rewrite system (TRS) terminates iff its rules are contained in a reduction ordering ?. In order to deal with any set of equations, including inherently nonterminating ones (like commutativity), TRS have been generalised to ordered TRS (E; ?), where equations of E are applied in whatever direction agrees with ?. The confluence of terminating TRS is wellknown to be decidable, but for ordered TRS the decidability of confluence has been open. Here we show that the confluence of ordered TRS is decidable if ordering constraints for ? can be solved in an adequate way, which holds in particular for the class of LPO orderings. For sets E of constrained equations, confluence is shown to be undecidable. Finally, ground reducibility is proved undecidable for ordered TRS. 1 Introduction Term rewrite systems (TRS) have been applied to many problems in symbolic computation, automated theorem proving, program synthesis and verification, and logic programming among others. Two fundamental pr...
Solved Forms for Path Ordering Constraints
 in `In Proc. 10th International Conference on Rewriting Techniques and Applications (RTA
, 1999
"... . A usual technique in symbolic constraint solving is to apply transformation rules until a solved form is reached for which the problem becomes simple. Ordering constraints are wellknown to be reducible to (a disjunction of) solved forms, but unfortunately no polynomial algorithm deciding the ..."
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Cited by 11 (4 self)
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. A usual technique in symbolic constraint solving is to apply transformation rules until a solved form is reached for which the problem becomes simple. Ordering constraints are wellknown to be reducible to (a disjunction of) solved forms, but unfortunately no polynomial algorithm deciding the satisfiability of these solved forms is known. Here we deal with a different notion of solved form, where fundamental properties of orderings like transitivity and monotonicity are taken into account. This leads to a new family of constraint solving algorithms for the full recursive path ordering with status (RPOS), and hence as well for other path orderings like LPO, MPO, KNS and RDO, and for all possible total precedences and signatures. Apart from simplicity and elegance from the theoretical point of view, the main contribution of these algorithms is on efficiency in practice. Since guessing is minimized, and, in particular, no linear orderings between the subterms are guessed, ...
Induction = IAxiomatization + FirstOrder Consistency
 Information and Computation
, 1998
"... In the early 80's, there was a number of papers on what should be called proofs by consistency. They describe how to perform inductive proofs, without using an explicit induction scheme, in the context of equational specifications and groundconvergent rewrite systems. The method was explici ..."
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Cited by 10 (0 self)
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In the early 80's, there was a number of papers on what should be called proofs by consistency. They describe how to perform inductive proofs, without using an explicit induction scheme, in the context of equational specifications and groundconvergent rewrite systems. The method was explicitly stated as a firstorder consistency proof in case of pure equational, constructor based, specifications. In this paper, we show how, in general, inductive proofs can be reduced to firstorder consistency and hence be performed by a firstorder theorem prover. Moreover, we extend previous methods, allowing nonequational specifications (even nonHorn specifications), designing some specific strategies. Finally, we also show how to drop the ground convergence requirement (which is called saturatedness for general clauses). 1 http://www.lsv.enscachan.fr/Publis/ Research Report LSV989, Lab. Spcification et Vrification, CNRS & ENS de Cachan, France, Oct. 1998 This paper was presente...
Theorem Proving in Cancellative Abelian Monoids
, 1996
"... We describe a refined superposition calculus for cancellative abelian monoids. They encompass not only abelian groups, but also such ubiquitous structures as the natural numbers or multisets. Both the AC axioms and the cancellation law are difficult for a general purpose superposition theorem prover ..."
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Cited by 9 (1 self)
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We describe a refined superposition calculus for cancellative abelian monoids. They encompass not only abelian groups, but also such ubiquitous structures as the natural numbers or multisets. Both the AC axioms and the cancellation law are difficult for a general purpose superposition theorem prover, as they create many variants of clauses which contain sums. Our calculus requires neither explicit inferences with the theory clauses for cancellative abelian monoids nor extended equations or clauses. Improved ordering constraints allow us to restrict to inferences that involve the maximal term of the maximal sum in the maximal literal. Furthermore, the search space is reduced drastically by certain variable elimination techniques.
RPO constraint solving is in NP
, 1998
"... A new decision procedure for the existential fragment of ordering constraints expressed using the recursive path ordering is presented. This procedure is nondeterministic and checks whether a set of constraints is solvable over the given signature, i.e., the signature over which the terms in th ..."
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Cited by 8 (0 self)
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A new decision procedure for the existential fragment of ordering constraints expressed using the recursive path ordering is presented. This procedure is nondeterministic and checks whether a set of constraints is solvable over the given signature, i.e., the signature over which the terms in the constraints are defined. It is shown that this nondeterministic procedure runs in polynomial time, thus establishing the membership of this problem in the complexity class NP for the first time.
A Methodological View of Constraint Solving
, 1996
"... Constraints have become very popular during the last decade. Constraints allow to define sets of data by means of logical formulae. Our goal here is to survey the notion of constraint system and to give examples of constraint systems operating on various domains, such as natural, rational or real nu ..."
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Cited by 6 (2 self)
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Constraints have become very popular during the last decade. Constraints allow to define sets of data by means of logical formulae. Our goal here is to survey the notion of constraint system and to give examples of constraint systems operating on various domains, such as natural, rational or real numbers, finite domains, and term domains. We classify the different methods used for solving constraints, syntactic methods based on transformations, semantic methods based on adequate representations of constraints, hybrid methods combining transformations and enumerations. Examples are used throughout the paper to illustrate the concepts and methods. We also discuss applications of constraints to various fields, such as programming, operations research, and theorem proving. y CNRS and LRI, Bat. 490, Universit'e de Paris Sud, 91405 ORSAY Cedex, France fcomon, jouannaudg@lri.lri.fr z COSYTEC, Parc Club Orsay Universit'e, 4 Rue Jean Rostand, 91893 Orsay Cedex, France dincbas@cosytec.fr x ...
Rewritebased Deduction and Symbolic Constraints
 In Proceedings of the 16th International Conference on Automated Deduction, volume 1632 of LNAI
, 1997
"... Introduction Building a stateoftheart theorem prover requires the combination of at least three main ingredients: good theory, clever heuristics, and the necessary engineering skills to implement it all in an efficient way. Progress in each of these ingredients interacts in different ways. On t ..."
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Cited by 5 (2 self)
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Introduction Building a stateoftheart theorem prover requires the combination of at least three main ingredients: good theory, clever heuristics, and the necessary engineering skills to implement it all in an efficient way. Progress in each of these ingredients interacts in different ways. On the one hand, new theoretical insights replace heuristics by more precise and effective techniques. For example, the completeness proof of basic paramodulation [NR95,BGLS95] shows why no inferences below Skolem functions are needed, as conjectured by McCune in [McC90]. Regarding implementation techniques, adhoc algorithms for procedures like demodulation or subsumption are replaced by efficient, reusable, generalpurpose indexing data structures for which the time and space requirements are wellknown. But, on the other hand, theory also advances in other directions, producing new ideas for which the development of implementation techniques and heuristics that make
Data Structures and Algorithms for Automated Deduction with Equality
, 2000
"... Machine [War83] implementation for Prolog) are stored in an array similar to the WAM heap. It is an array of pairs h tag, address i, where tag can be ref or struct, that is, a function symbol f. The field address contains a heap address. Terms are stored on the heap as in the WAM: each function symb ..."
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Cited by 3 (2 self)
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Machine [War83] implementation for Prolog) are stored in an array similar to the WAM heap. It is an array of pairs h tag, address i, where tag can be ref or struct, that is, a function symbol f. The field address contains a heap address. Terms are stored on the heap as in the WAM: each function symbol of arity n is followed by n contiguous ref positions pointing to its arguments. Each uninstantiated variable corresponds to a ref position pointing to itself. For example, the heap below at the left contains f(x; g(x); g(x); y) at the address 20: . . . . . . 20 f 21 ref 21 22 ref 30 23 ref 30 24 ref 24 . . . . . . 30 g 31 ref 21 . . . . . . Note that in such a representation the whole term needs not to be contiguous, and that common subterms not only variables can be shared, like the subterm g(x) at position 30. Moreover, unlike it happens in other term representations, matching and unification operations do not need to deal with a partial substitution: du...