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48
A Linear Logical Framework
, 1996
"... We present the linear type theory LLF as the forAppeared in the proceedings of the Eleventh Annual IEEE Symposium on Logic in Computer Science  LICS'96 (E. Clarke editor), pp. 264275, New Brunswick, NJ, July 2730 1996. mal basis for a conservative extension of the LF logical framework. LLF c ..."
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Cited by 215 (44 self)
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We present the linear type theory LLF as the forAppeared in the proceedings of the Eleventh Annual IEEE Symposium on Logic in Computer Science  LICS'96 (E. Clarke editor), pp. 264275, New Brunswick, NJ, July 2730 1996. mal basis for a conservative extension of the LF logical framework. LLF combines the expressive power of dependent types with linear logic to permit the natural and concise representation of a whole new class of deductive systems, namely those dealing with state. As an example we encode a version of MiniML with references including its type system, its operational semantics, and a proof of type preservation. Another example is the encoding of a sequent calculus for classical linear logic and its cut elimination theorem. LLF can also be given an operational interpretation as a logic programming language under which the representations above can be used for type inference, evaluation and cutelimination. 1 Introduction A logical framework is a formal system desig...
Automating the Meta Theory of Deductive Systems
, 2000
"... not be interpreted as representing the o cial policies, either expressed or implied, of NSF or the U.S. Government. This thesis describes the design of a metalogical framework that supports the representation and veri cation of deductive systems, its implementation as an automated theorem prover, a ..."
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Cited by 79 (16 self)
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not be interpreted as representing the o cial policies, either expressed or implied, of NSF or the U.S. Government. This thesis describes the design of a metalogical framework that supports the representation and veri cation of deductive systems, its implementation as an automated theorem prover, and experimental results related to the areas of programming languages, type theory, and logics. Design: The metalogical framework extends the logical framework LF [HHP93] by a metalogic M + 2. This design is novel and unique since it allows higherorder encodings of deductive systems and induction principles to coexist. On the one hand, higherorder representation techniques lead to concise and direct encodings of programming languages and logic calculi. Inductive de nitions on the other hand allow the formalization of properties about deductive systems, such as the proof that an operational semantics preserves types or the proof that a logic is is a proof calculus whose proof terms are recursive functions that may be consistent.M +
Efficient Representation and Validation of Proofs
, 1998
"... This paper presents a logical framework derived from the Edinburgh Logical Framework (LF) [5] that can be used to obtain compact representations of proofs and efficient proof checkers. These are essential ingredients of any application that manipulates proofs as firstclass objects, such as a Proof ..."
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Cited by 60 (7 self)
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This paper presents a logical framework derived from the Edinburgh Logical Framework (LF) [5] that can be used to obtain compact representations of proofs and efficient proof checkers. These are essential ingredients of any application that manipulates proofs as firstclass objects, such as a ProofCarrying Code [11] system, in which proofs are used to allow the easy validation of properties of safetycritical or untrusted code. Our framework, which we call LF i , inherits from LF the capability to encode various logics in a natural way. In addition, the LF i framework allows proof representations without the high degree of redundancy that is characteristic of LF representations. The missing parts of LF i proof representations can be reconstructed during proof checking by an efficient reconstruction algorithm. We also describe an algorithm that can be used to strip the unnecessary parts of an LF representation of a proof. The experimental data that we gathered in the context of a Proof...
Unification via Explicit Substitutions: The Case of HigherOrder Patterns
 PROCEEDINGS OF JICSLP'96
, 1998
"... In [6] we have proposed a general higherorder unification method using a theory of explicit substitutions and we have proved its completeness. In this paper, we investigate the case of higherorder patterns as introduced by Miller. We show that our general algorithm specializes in a very convenient ..."
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Cited by 56 (14 self)
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In [6] we have proposed a general higherorder unification method using a theory of explicit substitutions and we have proved its completeness. In this paper, we investigate the case of higherorder patterns as introduced by Miller. We show that our general algorithm specializes in a very convenient way to patterns. We also sketch an efficient implementation of the abstract algorithm and its generalization to constraint simplification, which has yielded good experimental results at the core of a higherorder constraint logic programming language.
Efficient Representation and Validation of Logical Proofs
, 1997
"... This report describes a framework for representing and validating formal proofs in various axiomatic systems. The framework is based on the Edinburgh Logical Framework (LF) but is optimized for minimizing the size of proofs and the complexity of proof validation, by removing redundant representation ..."
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Cited by 44 (6 self)
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This report describes a framework for representing and validating formal proofs in various axiomatic systems. The framework is based on the Edinburgh Logical Framework (LF) but is optimized for minimizing the size of proofs and the complexity of proof validation, by removing redundant representation components. Several variants of representation algorithms are presented with the resulting representations being a factor of 15 smaller than similar LF representations. The validation algorithm is a reconstruction algorithm that runs about 7 times faster than LF typechecking. We present a full proof of correctness of the reconstruction algorithm and hints for the efficient implementation using explicit substitutions. We conclude with a quantitative analysis of the algorithms. This research was sponsored in part by the Advanced Research Projects Agency CSTO under the title "The Fox Project: Advanced Languages for Systems Software," ARPA Order No. C533, issued by ESC/ENS under Contract No. F1...
Refinement Types for Logical Frameworks
 Informal Proceedings of the Workshop on Types for Proofs and Programs
, 1993
"... We propose a refinement of the type theory underlying the LF logical framework by a form of subtypes and intersection types. This refinement preserves desirable features of LF, such as decidability of typechecking, and at the same time considerably simplifies the representations of many deductive s ..."
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Cited by 42 (9 self)
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We propose a refinement of the type theory underlying the LF logical framework by a form of subtypes and intersection types. This refinement preserves desirable features of LF, such as decidability of typechecking, and at the same time considerably simplifies the representations of many deductive systems. A subtheory can be applied directly to hereditary Harrop formulas which form the basis of Prolog and Isabelle. 1 Introduction Over the past two years we have carried out extensive experiments in the application of the LF Logical Framework [HHP93] to represent and implement deductive systems and their metatheory. Such systems arise naturally in the study of logic and the theory of programming languages. For example, we have formalized the operational semantics and type system of MiniML and implemented a proof of type preservation [MP91] and the correctness of a compiler to a variant of the Categorical Abstract Machine [HP92]. LF is based on a predicative type theory with dependent t...
The Learnability of Description Logics with Equality Constraints
 Machine Learning
, 1994
"... Although there is an increasing amount of experimental research on learning concepts expressed in firstorder logic, there are still relatively few formal results on the polynomial learnability of firstorder representations from examples. Most previous analyses in the pacmodel have focused on s ..."
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Cited by 36 (3 self)
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Although there is an increasing amount of experimental research on learning concepts expressed in firstorder logic, there are still relatively few formal results on the polynomial learnability of firstorder representations from examples. Most previous analyses in the pacmodel have focused on subsets of Prolog, and only a few highly restricted subsets have been shown to be learnable. In this paper, we will study instead the learnability of the restricted firstorder logics known as "description logics", also sometimes called "terminological logics" or "KLONEtype languages". Description logics are also subsets of predicate calculus, but are expressed using a different syntax, allowing a different set of syntactic restrictions to be explored. We first define a simple description logic, summarize some results on its expressive power, and then analyze its learnability. It is shown that the full logic cannot be tractably learned. However, syntactic restrictions exist that enable tractable learning from positive examples alone, independent of the size of the vocabulary used to describe examples. The learnable sublanguage appears to be incomparable in expressive power to any subset of firstorder logic previously known to be learnable.
Automated Theorem Proving in a Simple MetaLogic for LF
 PROCEEDINGS OF THE 15TH INTERNATIONAL CONFERENCE ON AUTOMATED DEDUCTION (CADE15
, 1998
"... Higherorder representation techniques allow elegant encodings of logics and programming languages in the logical framework LF, but unfortunately they are fundamentally incompatible with induction principles needed to reason about them. In this paper we develop a metalogic M_2 which allows i ..."
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Cited by 35 (16 self)
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Higherorder representation techniques allow elegant encodings of logics and programming languages in the logical framework LF, but unfortunately they are fundamentally incompatible with induction principles needed to reason about them. In this paper we develop a metalogic M_2 which allows inductive reasoning over LF encodings, and describe its implementation in Twelf, a specialpurpose automated theorem prover for properties of logics and programming languages. We have used Twelf to automatically prove a number of nontrivial theorems, including type preservation for MiniML and the deduction theorem for intuitionistic propositional logic.
Proof Terms for Simply Typed Higher Order Logic
 IN THEOREM PROVING IN HIGHER ORDER LOGICS, 13TH INTERNATIONAL CONFERENCE, VOLUME 1869 OF LNCS
, 2000
"... This paper presents proof terms for simply typed, intuitionistic higher order logic, a popular logical framework. Unificationbased algorithms for the compression and reconstruction of proof terms are described and have been implemented in the theorem prover Isabelle. Experimental results confir ..."
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Cited by 34 (8 self)
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This paper presents proof terms for simply typed, intuitionistic higher order logic, a popular logical framework. Unificationbased algorithms for the compression and reconstruction of proof terms are described and have been implemented in the theorem prover Isabelle. Experimental results confirm the effectiveness of the compression scheme.
Implementing the MetaTheory of Deductive Systems
 Proceedings of the 11th International Conference on Automated Deduction
, 1992
"... . We exhibit a methodology for formulating and verifying metatheorems about deductive systems in the Elf language, an implementation of the LF Logical Framework with an operational semantics in the spirit of logic programming. It is based on the mechanical verification of properties of transformatio ..."
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Cited by 32 (9 self)
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. We exhibit a methodology for formulating and verifying metatheorems about deductive systems in the Elf language, an implementation of the LF Logical Framework with an operational semantics in the spirit of logic programming. It is based on the mechanical verification of properties of transformations between deductions, which relies on type reconstruction and schemachecking. The latter is justified by induction principles for closed LF objects, which can be constructed over a given signature. We illustrate our technique through several examples, the most extensive of which is an interpretation of classical logic in minimal logic through a continuationpassingstyle transformation on proofs. 1 Introduction Formal deductive systems have become an important tool in computer science. They are used to specify logics, type systems, operational semantics and other aspects of languages. The role of such specifications is threefold. Firstly, inference rules serve as a highlevel notation w...