Category Archives: research

One big issue in the logic programming vs functional programming debate is logic programming’s (or at least the original Prolog’s) restriction to first order logic. To functional programmers this constraint is intolerable; even the simplest Haskell programs are higher order … Continue reading →

When I was a young grad student at UC Berkeley, I invented what are now called “Wadge degrees”. Not to mention “Wadge reducibility”, “Wadge games”, “Wadge’s Lemma” and the “Wadge hierarchy”  (there’s a Wikipedia entry on the latter). “So”, I … Continue reading →

I remember when, a long time ago, Logic Programming was just starting out. The logic programmers would go to the functional programming gatherings and hang around the sidelines, hoping to convince everyone that logic programming was a kind of functional … Continue reading →

The Universal Hybrid Calculus (UHC) is a simple logical formalism that has the power of the monadic predicate calculus but has no bound variables. Natural language statements (which also do not use variables) can be formulated more directly in the … Continue reading →

Besides the development  of  Lucid, for a long while I’ve been working on another application of intensionality, namely intensional web pages – pages whose exact content depends on an implicit context. Unlike with Lucid, the contexts are not lists of … Continue reading →

Here is the promised description of the retirement plan mentioned in the Lucid – Eduction post. This description is a slightly edited version of section 3 of “An eductive interpreter for the language pLucid”, by myself and A. Faustini, which … Continue reading →

One way of understanding the problem described in “Into the Abyss” is in terms of the domain of streams being used. The data-push model, discovered originally by Gilles Kahn, models a stream as either a finite or infinite sequence of … Continue reading →

When we discovered the dataflow interpretation of Lucid (see post, Lucid, the dataflow language) we thought we’d found the promised land. We had an attractive computing model that was nevertheless faithful to the declarative semantics of statements-as-equations. However, there was … Continue reading →

Recently I’ve been working with my wife Christine (who teaches in the French Department at UVIC) on a simple system, called Quiz Script, that makes it easy and quick to generate online interactive quizzes. This is the handout we gave … Continue reading →

In the last post I explained how temporal logic came to the rescue and enabled equations like next(I) = I+1 to be interpreted as real equations. In this temporal logic variables like I are variables that change with time – … Continue reading →