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Biform theories in Chiron
 Towards Mechanized Mathematical Assistants, volume 4573 of Lecture Notes in Computer Science
, 2007
"... Abstract. An axiomatic theory represents mathematical knowledge declaratively as a set of axioms. An algorithmic theory represents mathematical knowledge procedurally as a set of algorithms. A biform theory is simultaneously an axiomatic theory and an algorithmic theory. It represents mathematical k ..."
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Cited by 8 (5 self)
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Abstract. An axiomatic theory represents mathematical knowledge declaratively as a set of axioms. An algorithmic theory represents mathematical knowledge procedurally as a set of algorithms. A biform theory is simultaneously an axiomatic theory and an algorithmic theory. It represents mathematical knowledge both declaratively and procedurally. Since the algorithms of algorithmic theories manipulate the syntax of expressions, biform theories—as well as algorithmic theories—are difficult to formalize in a traditional logic without the means to reason about syntax. Chiron is a derivative of vonNeumannBernaysGödel (nbg) set theory that is intended to be a practical, generalpurpose logic for mechanizing mathematics. It includes elements of type theory, a scheme for handling undefinedness, and a facility for reasoning about the syntax of expressions. It is an exceptionally wellsuited logic for formalizing biform theories. This paper defines the notion of a biform theory, gives an overview of Chiron, and illustrates how biform theories can be formalized in Chiron. 1
Communicating and trusting proofs: The case for broad spectrum proof certificates. Available from author’s website
, 2011
"... Abstract. Proofs, both formal and informal, are documents that are intended to circulate within societies of humans and machines distributed across time and space in order to provide trust. Such trust might lead one mathematician to accept a certain statement as true or it might help convince a cons ..."
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Cited by 2 (2 self)
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Abstract. Proofs, both formal and informal, are documents that are intended to circulate within societies of humans and machines distributed across time and space in order to provide trust. Such trust might lead one mathematician to accept a certain statement as true or it might help convince a consumer that a certain software system is secure. Using this general characterization of proofs, we examine a range of perspectives about proofs and their roles within mathematics and computer science that often appear contradictory. We then consider the possibility of defining a broad spectrum proof certificate format that is intended as a universal language for communicating formal proofs among computational logic systems. We identify four desiderata for such proof certificates: they must be (i) checkable by simple proof checkers, (ii) flexible enough that existing provers can conveniently produce such certificates from their internal evidence of proof, (iii) directly related to proof formalisms used within the structural proof theory literature, and (iv) permit certificates to elide some proof information with the expectation that a proof checker can reconstruct the missing information using bounded and structured proof search. We consider various consequences of these desiderata, including how they can mix computation and deduction and what they mean for the establishment of marketplaces and libraries of proofs. In a companion paper we proposal a specific framework for achieving all four of these desiderata. 1
(ULTRA group, HeriotWatt University)
"... Abstract. In only few decades, computers have changed the way we approach documents. Throughout history, mathematicians and philosophers had clarified the relationship between mathematical thoughts and their textual and symbolic representations. We discuss here the consequences of computerbased for ..."
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Abstract. In only few decades, computers have changed the way we approach documents. Throughout history, mathematicians and philosophers had clarified the relationship between mathematical thoughts and their textual and symbolic representations. We discuss here the consequences of computerbased formalisation for mathematical authoring habits and we present an overview of our approach for computerising mathematical texts. 1.
My Fourty Years on His Shoulders
, 2008
"... Gödel's legacy is still very much in evidence. His legacy is overwhelmingly decisive, particularly in the arena of general mathematical and philosophical inquiry. The extent of Gödel's impact in the more restricted domain of mathematical practice is more open to question. In fact, there is an in de ..."
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Gödel's legacy is still very much in evidence. His legacy is overwhelmingly decisive, particularly in the arena of general mathematical and philosophical inquiry. The extent of Gödel's impact in the more restricted domain of mathematical practice is more open to question. In fact, there is an in depth assessment of this impact in Macintyre 2009. But even in this comparatively specialized domain, Gödel's impact is seen to be substantial. As indicated here, particularly in section 12, we believe that the potential impact of Gödel's work 2 on mathematical practice is also overwhelming. However, the full realization of this potential impact will have to wait for some new breakthroughs. We have every confidence that these breakthroughs will materialize. Generally speaking, current mathematical practice has now become very far removed from general mathematical and philosophical inquiry, where Gödel's legacy is most decisively overwhelming. However, there are some signs that some of our most distinguished mathematicians recognize the need for some sort of reconciliation. Here is a quote from Atiyah M. 2008b: "Mathematicians took the role of philosophers, but I want to bring the philosophers back in. I hope someday we will be able to explain mathematics in a philosophical way using philosophical methods". We will not attempt to properly discuss the full impact of Gödel's work and all of the ongoing important research programs that it suggests. This would require a book length manuscript. Indeed, there are several books discussing the Gödel legacy from many points of view, including, for example, (Wang 1987, 1996), (Dawson 2005), and the historically comprehensive five volume set (Gödel
1. General Remarks. 2. The Completeness Theorem. 3. The First Incompleteness Theorem. 4. The Second Incompleteness Theorem.
, 2006
"... several historical points. 1. GENERAL REMARKS Gödel's legacy is still very much in evidence. His legacy is overwhelmingly decisive, particularly in the arena of general mathematical and2 philosophical inquiry. The extent of Gödel's impact in the more restricted domain of mathematical practice is mor ..."
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several historical points. 1. GENERAL REMARKS Gödel's legacy is still very much in evidence. His legacy is overwhelmingly decisive, particularly in the arena of general mathematical and2 philosophical inquiry. The extent of Gödel's impact in the more restricted domain of mathematical practice is more open to question. In fact, there is an in depth assessment of this impact in Macintyre 2009. But even in this comparatively specialized domain, Gödel's impact is seen to be substantial. As indicated here, particularly in section 12, we believe that the potential impact of Gödel's work on mathematical practice is also overwhelming. However, the full realization of this potential impact will have to wait for some new breakthroughs. We have every confidence that these breakthroughs will materialize. Generally speaking, current mathematical practice has now become very far removed from general mathematical and philosophical inquiry, where Gödel's legacy is most decisively overwhelming. However, there are some signs that some of our most distinguished mathematicians recognize the need for some sort of reconciliation. Here is a quote from Atiyah M. 2008b: "Mathematicians took the role of philosophers, but I want to bring the philosophers back in. I hope someday we will be able to explain mathematics in a philosophical way using philosophical methods".3 We will not attempt to properly discuss the full impact of Gödel's work and all of the ongoing important research programs that it suggests. This would require a book length manuscript. Indeed, there are several books discussing the Gödel legacy from many points of view, including, for example, (Wang 1987, 1996), (Dawson 2005), and the historically comprehensive five volume set (Gödel
Communicating and trusting proofs: The case for foundational proof certificates
"... It is well recognized that proofs serve two different goals. On one hand, they can serve the didactic purpose of explaining why a theorem holds: that is, a proof has a message that is meant to describe the “why ” behind a theorem. On the other hand, proofs can serve as certificates of validity. In t ..."
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It is well recognized that proofs serve two different goals. On one hand, they can serve the didactic purpose of explaining why a theorem holds: that is, a proof has a message that is meant to describe the “why ” behind a theorem. On the other hand, proofs can serve as certificates of validity. In this case, once a certificate
Decidability and Undecidability Results for Propositional Schemata
"... We define a logic of propositional formula schemata adding to the syntax of propositional logic indexed propositions (e.g., pi) and iterated connectives ∨ or ∧ ranging over intervals parameterized by arithmetic variables (e.g., ∧n i=1 pi, where n is a parameter). The satisfiability problem is shown ..."
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We define a logic of propositional formula schemata adding to the syntax of propositional logic indexed propositions (e.g., pi) and iterated connectives ∨ or ∧ ranging over intervals parameterized by arithmetic variables (e.g., ∧n i=1 pi, where n is a parameter). The satisfiability problem is shown to be undecidable for this new logic, but we introduce a very general class of schemata, called boundlinear, for which this problem becomes decidable. This result is obtained by reduction to a particular class of schemata called regular, for which we provide a sound and complete terminating proof procedure. This schemata calculus (called stab) allows one to capture proof patterns corresponding to a large class of problems specified in propositional logic. We also show that the satisfiability problem becomes again undecidable for slight extensions of this class, thus demonstrating that boundlinear schemata represent a good compromise between expressivity and decidability. 1.
Closing the Gap Between Formal and Digital Libraries of Mathematics
"... Abstract. The representational gap between formal mathematics and most users of digital mathematics resources is a challenge for any approach to mathematical knowledge management which aims to combine the benefits of formal and informal mathematics. In this chapter we study this gap in the context o ..."
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Abstract. The representational gap between formal mathematics and most users of digital mathematics resources is a challenge for any approach to mathematical knowledge management which aims to combine the benefits of formal and informal mathematics. In this chapter we study this gap in the context of a digital library of mathematics based on the Mizar Mathematical Library and make recommendations for improving such formal systems support for MKM. 1