Hello, might be interested that my Morph Gentzen project since 1995, Virtual Geometry, ADG Zurich 2003, and two books published 1999 http://www.lulu.com/CrisFN, 2005 http://www.aspbs.com/mutlimedia.html are on a diagrammatic,categorial initial algebras, and structures on Lw1,w. Cyrus

----- Original Message ----- From: "John Baez" <baez@math.ucr.edu> To: categories@mta.ca Subject: categories: universal algebra and diagrammatic reasoning Date: Thu, 26 Jan 2006 13:09:36 -0800 (PST)

Hi -

I hope to see some of you in Marseille for Geocal06! I'll be talking about "universal algebra and diagrammatic reasoning", and there's a bunch of lecture notes here:

http://math.ucr.edu/home/baez/universal/

Abstract:

Since the introduction of category theory, the old subject of "universal algebra" has diversified into a large collection of frameworks for describing algebraic structures. These include "monads" (formerly known as "triples"), the "algebraic theories" of Lawvere, and the "PROPs" of Boardman and Vogt. We give an overview of these different frameworks, which are closely related, and explain how one can reason diagrammatically about algebraic structures defined using them. We focus on the bar construction and the relation between algebraic theories and PROPs.

(I feel guilty for not talking about operads... I'll do it if there's time!)

Best, jb

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