Jay Gischer

Bio: Jay Gischer is an academic researcher from University of Washington. The author has contributed to research in topics: Regular expression & Concurrency. The author has an hindex of 1, co-authored 1 publications receiving 75 citations.

Shuffle languages, Petri nets, and context-sensitive grammars

Abstract: Flow expressions have been proposed as an extension of the regular expressions designed to model concurrency. We examine a simplification of these flow expressions which we call shuffle expressions. We introduce two types of machines to aid in recognizing shuffle languages and show that one such machine may be equivalent to a Petri Net. In addition, closure and containment properties of the related language classes are investigated, and we show that one machine type recognizes at least a restricted class of shuffle languages. Finally, grammars for all shuffle languages are generated, and the shuffle languages are shown to be context-sensitive.

Two-Variable Logic on Words with Data

Abstract: In a data word each position carries a label from a finite alphabet and a data value from some infinite domain. These models have been already considered in the realm of semistructured data, timed automata and extended temporal logics. It is shown that satisfiability for the two-variable first-order logic FO^2(~,\le,+1) is decidable over finite and over infinite data words, where i« is a binary predicate testing the data value equality and +1,\le are the usual successor and order predicates. The complexity of the problem is at least as hard as Petri net reachability. Several extensions of the logic are considered, some remain decidable while some are undecidable.

Two-variable logic on data words

Abstract: In a data word each position carries a label from a finite alphabet and a data value from some infinite domain. This model has been already considered in the realm of semistructured data, timed automata, and extended temporal logics.This article shows that satisfiability for the two-variable fragment FO2(∼,

Resource Usage Analysis.

Abstract: It is an important criterion of program correctness that a program accesses resources in a valid manner. For example, a memory region that has been allocated should eventually be deallocated, and after the deallocation, the region should no longer be accessed. A file that has been opened should be eventually closed. So far, most of the methods to analyze this kind of property have been proposed in rather specific contexts (like studies of memory management and verification of usage of lock primitives), and it was not clear what the essence of those methods was or how methods proposed for individual problems are related. To remedy this situation, we formalize a general problem of analyzing resource usage as a resource usage analysis problem, and propose a type-based method as a solution to the problem.

Resource usage analysis

Abstract: It is an important criterion of program correctness that a program accesses resources in a valid manner. For example, a memory region that has been allocated should be eventually deallocated, and after the deallocation, the region should no longer be accessed. A file that has been opened should be eventually closed. So far, most of the methods to analyze this kind of property have been proposed in rather specific contexts (like studies of memory management and verification of usage of lock primitives), and it was not so clear what is the essence of those methods or how methods proposed for individual problems are related. To remedy this situation, we formalize a general problem of analyzing resource usage as a resource usage analysis problem, and propose a type-based method as a solution to the problem.