Horn equational theories and paramodulation

A language of equational programs together with an inference system, based on paramodulation is defined. The semantics of the language is given with respect to least models, least fixpoints and success sets and its soundness and completeness is proven using fixpoint theory. The necessity of the functional reflexive axioms is investigated in detail. Finally, the application of these ideas to term rewriting systems is outlined by discussing directed paramodulation and narrowing.     

Solution of the Robbins Problem

In this article we show that the three equations known as commutativity,associativity, and the Robbins equation are a basis for the variety ofBoolean algebras. The problem was posed by Herbert Robbins in the 1930s. Theproof was found automatically by EQP, a theorem-proving program forequational logic. We present the proof and the search strategies thatenabled the program to find the proof.     

一个带有相似性关系的模糊逻辑

模糊集与模糊逻辑是处理模糊性与不确定性信息的重要数学工具,相似性关系是模糊集的一个基本概念。为了在模糊逻辑中集成相似性关系并考虑其模糊推理,提出了一个带有相似性关系的模糊逻辑,给出了其语法及语义描述,在模糊谓词逻辑情形下,讨论并证明了基于归结与调解方法的模糊推理的有关属性,考虑到许多定理证明器和问题解决系统均是基于否证法,证明了归结与调解方法对模糊谓词演算的反驳完备性定理。     

The problem of reasoning from inequalities

This article is the twenty-first of a series of articles discussing various open research problems in automated reasoning. The problem proposed for research asks one to find an inference rule that performs as paramodulation does, but with the focus on inequalities rather than on equalities. Since, too often, inequalities that are present in the input play a passive role during a reasoning program's attempt to complete an assignment, such an inference rule would markedly add to program effectiveness by giving inequalities the potential of playing a key role. For evaluating a proposed solution to this research problem, we suggest as possible test problems theorems from group theory and theorems from ring theory. This work was supported by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under Contract W-13-109-Eng-38.     

广义Horn集

本文定义了广义Ｈｏｒｎ集，并在广义Ｈｏｒｎ集上证明了广义输入归结的完备性；广义输入对称调解的完备性；以及一定条件下的广义输入有向调解的完备性．文中还证明了广义调解法的提升引理．     

The problem of finding a strategy to control binary paramodulation

This article is the fifth of a series of articles discussing various open research problems in automated reasoning. Here we focus on the equality relation which is so vital to many applications of automated reasoning. The prolem proposed for research asks one to find a strategy for controlling the application of binary paramodulation. For evaluating a proposed solution to this research problem, we include suggestions concerning possible test problems.This work was supported by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under contract W-31-109-Eng-38.     

The problem of choosing between using and avoiding equality predicates

This article is the twentieth of a series of articles discussing various open research problems in automated reasoning. The problem proposed for research asks one to find criteria for effectively choosing between using and avoiding equality predicates. Since there exist inference rules (such as paramodulation) that enable an automated reasoning program to treat equality as understood, the discovery of such criteria would mark an important advance for the field. For evaluating a proposed solution to this research problem, we suggest possible test problems from group theory, ring theory, and Boolean algebra.This work was supported by the Applied Mathematical Sciences subprogram of the Office of Energy Research, U.S. Department of Energy, under Contract W-31-109-Eng-38.     

Tree automata with equality constraints modulo equational theories

This paper presents new classes of tree automata combining automata with equality test and automata modulo equational theories. We believe that these classes have a good potential for application in e.g. software verification. These tree automata are obtained by extending the standard Horn clause representations with equational conditions and rewrite systems. We show in particular that a generalized membership problem (extending the emptiness problem) is decidable by proving that the saturation of tree automata presentations with suitable paramodulation strategies terminates. Alternatively our results can be viewed as new decidable classes of first-order formula.     

Uniform strategies: The CADE-11 theorem proving contest

At CADE-10 Ross Overbeek proposed a two-part contest to stimulate and reward work in automated theorem proving. The first part consists of seven theorems to be proved with resolution, and the second part of equational theorems. Our theorem proversOtter and its parallel childRoo proved all of the resolution theorems and half of the equational theorems. This paper represents a family of entries in the contest.