some new preprints/presentation

"Modelling and Computing Homotopy Types: I" (now published in Indagationes Math) 25 pages (Sections 1,2 of this paper outline a philosophy and methodology for using strict higher groupoids in algebraic topology) "Higher dimensional modelling and rewriting in algebraic topology" 7 pages "Homotopical Excision: (work to be done!)" (beamer presentation: 19 pages) (This last begins a new look at the excision theorem of the 1987 paper with Loday "Homotopical Excision and Hurewicz Theorems for n-cubes of spaces". ) These are available at http://groupoids.org.uk/brownpr.html Best wishes Ronnie [For admin and other information see: http://www.mta.ca/~cat-dist/ ]