Calculus without limits

# Geometry of Delta Sets

In this presentation, there is a bit of advertisement for finite geometry and delta sets in particular. I also tried to get a bit into the history of finitist ideas in geometry and physics(starting with Riemann). One usually thinks about finite projective spaces when talking about “finite geometries”. I like to think about objects like finite graphs, quivers, simplicial complexes or delta sets as “finite geometries”. For me, an object starts to be geometric, if it has a derivative and so cohomology. Sets or “sets of sets”=hyper (sgraphs are geometric objects also but they are mostly 0 dimensional in that the derivative that is constant 0 is the only possibility. That means they are zero dimensional objects. Already any finite simple graph has a higher dimensional geometry, where the dimension is the dimension of the maximal implex (clique) contained in the graph. Maybe something is original in the talk: I give a recursive 2 line code to compute all the complete subgraphs (cliques) of a graph. It is a simple recursive algorithm using the fact that the cone extensions of the cliques of the unit spheres make the cliques of the graph.