This is a description of TPS, a theorem proving system for classical type theory (Church’s typed λ-calculus). TPS has been designed to be a general research tool for manipulating wffs of first- and higher-order logic, and searching for proofs of such wffs interactively or automatically, or in a combination of these modes. An important feature of TPS is the ability to translate between expansion proofs and natural deduction proofs. Examples of theorems which TPS can prove completely automatically are given to illustrate certain aspects of TPS’s behavior and problems of theorem proving in higher-order logic. 7

Most automated theorem provers suffer from the problem that they can produce proofs only in formalisms difficult to understand even for experienced mathematicians. Effort has been made to reconstruct natural deduction (ND) proofs from such machine generated proofs. Although the single steps in ND proofs are easy to understand, the entire proof is usually at a low level of abstraction, containing too many tedious steps. To obtain proofs similar to those found in mathematical textbooks, we propose a new formalism, called ND style proofs at the assertion level , where derivations are mostly justified by the application of a definition or a theorem. After characterizing the structure of compound ND proof segments allowing assertion level justification, we show that the same derivations can be achieved by domain-specific inference rules as well. Furthermore, these rules can be represented compactly in a tre structure. Finally, we describe a system called PROVERB , which substantially sh...

TPS is a theorem proving system for first- and higher-order logic which runs in Common Lisp and can operate in automatic, semi-automatic, and interactive modes. As its logical language TPS uses the typed A-calculus [6], in which most theorems of mathematics can be expressed very directly. TPS can be used to search for an expansion proof [10, 11] of a theorem, which represents in a nonredtmdant way the basic combinatorial information required to construct a proof of

. This is description of TPS, a theorem-proving system for classical type theory (Church's typed #-calculus). TPS has been designed to be a general research tool for manipulating wffs of first- and higher-order logic, and searching for proofs of such wffs interactively or automatically, or in a combination of these modes. An important feature of TPS is the ability to translate between expansion proofs and natural deduction proofs. Examples of theorems that TPS can prove completely automatically are given to illustrate certain aspects of TPS's behavior and problems of theorem proving in higher-order logic. AMS Subject Classification: 03-04, 68T15, 03B35, 03B15, 03B10. Key words: higher-order logic, type theory, mating, connection, expansion proof, natural deduction. 1. Introduction TPS is a theorem-proving system for classical type theory ## (Church's typed #-calculus [20]) which has been under development at Carnegie Mellon University for a number years. This paper gives a general...

Introduction This is a brief update on the Tps automated theorem proving system for classical type theory, which was described in [3]. Manuals and information about obtaining Tps can be found at http://gtps.math.cmu.edu/tps.html. In Section 2 we discuss some examples of theorems which Tps can now prove automatically, and in Section 3 we discuss an example which illustrates one of the many challenges of theorem proving in higher-order logic. We rst provide a brief summary of the key features of Tps . Tps uses Church's type theory [8] (typed -calculus) as its logical language. Ws are displayed on the screen and in printed proofs in the notation of this system of symbolic logic. One can use Tps in automatic, semi-automatic, or interactive mode to construct proofs in natural deduction style, and a mixture of these modes of operation is most useful fo

Most automated theorem provers suffer from the problem that the resulting proofs are difficult to understand even for experienced mathematicians. An effective communication between the system and its users, however, is crucial for many applications, such as in a mathematical assistant system. Therefore, efforts have been made to transform machine generated proofs (e.g. resolution proofs) into natural deduction (ND) proofs. The state-of-the-art procedure of proof transformation follows basically its completeness proof: the premises and the conclusion are decomposed into unit literals, then the theorem is derived by multiple levels of proofs by contradiction. Indeterminism is introduced by heuristics that aim at the production of more elegant results. This indeterministic character entails not only a complex search, but also leads to unpredictable results. In this paper we first study resolution proofs in terms of meaningful operations employed by human mathematicians, and thereby esta...

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Most automated theorem provers suffer on the problem that the proofs they produce are difficult to understand even for experienced users. Therefore, many efforts have been made to transform, abstract and restructure machine-found proofs to produce proof formats better understandable for humans. One of the most prefered target formats is the natural deduction proof. Current approaches suffer mainly on two problems. First, the state-ofthe -art transformation procedures generate very often natural deduction proofs with many indirect parts since they translate at the literal level steps from the machine-found proofs into the natural deduction proofs. Secondly, the natural deduction calculus itself is not eligible for presenting mathematical proofs. The problem is that inferences in the natural deduction calculus are still on the level of syntactical manipulations of logical connectives and quantifiers. They are not on the level of theorem or definition applications as we have in mathematic...

not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the sponsoring institutions, the U.S. Government or any other entity. Keywords: Formal methods, model checking, abstraction, refinement, bounded model checking, Boolean satisfiability, non-clausal SAT solvers, DPLL, general matings, unsatisfiable core, craig interpolation, proofs of unsatisfiability, linear diophantine equations, linear modular equations (linear congruences), linear diophantine Automatic verification of hardware and software implementations is crucial for building reliable computer systems. Most verification tools rely on decision procedures to check the satisfiability of various formulas that are generated during the verification process. This thesis develops new techniques for building efficient decision procedures and adds new capabilities to the existing decision procedures for certain logics. Boolean satisfiability (SAT) solvers are used heavily in verification tools as decision procedures for propositional logic. Most state-of-the-art SAT solvers are

Abstract: Logic calculi, and Gentzen-type calculi in particular, can be categorised into two types: search-oriented and interaction-oriented calculi. Both these types have certain inherentcharacteristics stemming from the purpose for which they are designed. In this paper, we give a general characterisation of the two types and present two calculi that are typical representatives of their respective class. We introduce a method for transforming proofs in the search-oriented calculus into proofs in the interactionoriented calculus, and we demonstrate that the di culties arising with devising such a transformation do not pertain to the speci c calculi we have chosen as examples but are general. We also give examples for the application of our transformation procedure.