Relational characterisations of paths

Relational Characterisations of Paths

Binary relations are one of the standard ways to encode, characterise and reason about graphs. Relation algebras provide equational axioms for a large fragment of the calculus of binary relations. Although relations are standard tools in many areas of mathematics and computing, researchers usually fall back to point-wise reasoning when it comes to arguments about paths in a graph. We present a ...

Mining Relational Paths in Integrated Biomedical Data

Much life science and biology research requires an understanding of complex relationships between biological entities (genes, compounds, pathways, diseases, and so on). There is a wealth of data on such relationships in publicly available datasets and publications, but these sources are overlapped and distributed so that finding pertinent relational data is increasingly difficult. Whilst most p...

Geometric Characterisations of Groups

Characterisations of Nelson Algebras

Nelson algebras arise naturally in algebraic logic as the algebraic models of Nelson’s constructive logic with strong negation. This note gives two characterisations of the variety of Nelson algebras up to term equivalence, together with a characterisation of the finite Nelson algebras up to polynomial equivalence. The results answer a question of Blok and Pigozzi and clarify some earlier work ...

Evaluation of Access Paths in a Relational Database System

De Jong,David Peter.MS. ,Purdue University.Nuy1978.Evaluation of Access Paths in a Relational Database System.Najor Professor: S. B. Yao. The motivation for and concepts of a relational database organization are briefly reviewed, and a ~eneral model of acc~ss paths for a relational database is described. As a tool for access path desicn and selection a series of equations are developed for the ...