Two affine algebraic curves over the complex numbers are in bad position if they have at least two distinct common points on some vertical line, i.e. for some Î± âˆˆ C there are distinct Î²1, Î²2 âˆˆ C suchâ€¦ (More)

At the 1976 Oxford Conference, Aanderaa introduced a new class of machines which he called F machines (later renamed as modular machines). Using these he gave two remarkably short and easy examplesâ€¦ (More)

The unsolvability of the conjugacy problem for finitely presented groups was first shown by Novikov [26]. Shortly thereafter the corresponding result for the word problem was proved by Novikov [27]â€¦ (More)

We discuss an algebraic method for model checking in the modal Î¼-calculus over finite state labelled transition systems that can be used to provide solutions that are in a sense generic, i.e., in aâ€¦ (More)

GrÃ¶bner bases were introduced by Buchberger (1965) and are now firmly established as a tool in Commutative Algebra and other areas. The reader is referred to Buchberger (1985), Cox, Little and Oâ€™Sheaâ€¦ (More)

We use a rank-based measure on rational expressions in indeterminates over a field and define notions of size and depth with associated subparts of formulae for expressions. Formulae are allowed toâ€¦ (More)

We consider the problem of describing GrÃ¶bner-Shirshov bases for free associative algebras in finite terms. To this end we consider parametrised elements of an algebra and give methods for workingâ€¦ (More)