Focusing and Polarization in Intuitionistic Logic

A focused proof system provides a normal form to cut-free proofs that structures the application of invertible and non-invertible inference rules. The focused proof system of Andreoli for linear logic has been applied to both the proof search and the proof normalization approaches to computation. Various proof systems in literature exhibit characteristics of focusing to one degree or another. We present a new, focused proof system for intuitionistic logic, called LJF, and show how other proof systems can be mapped into the new system by inserting logical connectives that prematurely stop focusing. We also use LJF to design a focused proof system for classical logic. Our approach to the design and analysis of these systems is based on the completeness of focusing in linear logic and on the notion of polarity that appears in Girard's LC and LU proof systems

About a Mature Theory of Fregean Sense

Marie Duží, Bjørn Jespersen, and Pavel Materna: Procedural Semantics for Hyperintensional Logic. Foundations and Applications of Transparent Intentional Logic, vol. 17 of series “Logic, Epistemology, and the Unity of Science”, Springer, Dordrecht, Heidelberg, London, New York, 2010; xiii+552 pages, ISBN 978-90-481-8811-6, e-ISBN 978-90-481-8812-3. DOI: 10.1007/978-90-481-8812-

Beyond Polarity: Towards a Multi-Discipline Intermediate Language with Sharing

The study of polarity in computation has revealed that an "ideal" programming language combines both call-by-value and call-by-name evaluation; the two calling conventions are each ideal for half the types in a programming language. But this binary choice leaves out call-by-need which is used in practice to implement lazy-by-default languages like Haskell. We show how the notion of polarity can be extended beyond the value/name dichotomy to include call-by-need by only adding a mechanism for sharing and the extra polarity shifts to connect them, which is enough to compile a Haskell-like functional language with user-defined types

The Montana Kaimin, June 6, 1947

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/3302/thumbnail.jp

Preemptive type checking in dynamically typed programs

With the rise of languages such as JavaScript, dynamically typed languages have gained a strong foothold in the programming language landscape. These languages are very well suited for rapid prototyping and for use with agile programming methodologies. However, programmers would benefit from the ability to detect type errors in their code early, without imposing unnecessary restrictions on their programs.Here we describe a new type inference system that identifies potential type errors through a flow-sensitive static analysis. This analysis is invoked at a very late stage, after the compilation to bytecode and initialisation of the program. It computes for every expression the variable’s present (from the values that it has last been assigned) and future (with which it is used in the further program execution) types, respectively. Using this information, our mechanism inserts type checks at strategic points in the original program. We prove that these checks, inserted as early as possible, preempt type errors earlier than existing type systems. We further show that these checks do not change the semantics of programs that do not raise type errors.Preemptive type checking can be added to existing languages without the need to modify the existing runtime environment. We show this with an implementation for the Python language and demonstrate its effectiveness on a number of benchmarks

The Rose Tech Explorer - May 27, 1960

https://scholar.rose-hulman.edu/rose_tech_explorer/1013/thumbnail.jp

The Missouri Miner, January 30, 1974

https://scholarsmine.mst.edu/missouri_miner/3050/thumbnail.jp

Montana Kaimin, September 11, 1997

Student newspaper of the University of Montana, Missoula.https://scholarworks.umt.edu/studentnewspaper/10150/thumbnail.jp