2008/08/05 by James Conant, Conant, James, Oliver Thistlethwaite +1
Mathematics · #05C65 #55P15 #68Q15 #Algebraic Topology (math.AT) #Combinatorics (math.CO) #FOS: Mathematics #math.AT #math.CO #msc:05C65 #msc:55P15 #msc:68Q15
paper · pdf · doi:10.48550/arxiv.0808.0739
Added discussion of independence complex and new computer calculations. Added coauthor Oliver Thistlethwaite. To appear in Topology and its Applications
arxiv created 2010/08/23 · arxiv updated 2010/08/24
With a view toward studying the homotopy type of spaces of Boolean formulae, we introduce a simplicial complex, called the theta complex, associated to any hypergraph, which is the Alexander dual of the more well-known independence complex. In particular, the set of satisfiable formulae in k-conjunctive normal form with less than or equal to n variables has the homotopy type of Theta(Cube(n,n-k)), where Cube(n,n-k) is a hypergraph associated to the (n-k)-skeleton of an n-cube. We make partial progress in calculating the homotopy type of theta for these cubical hypergraphs, and we also give calculations and examples for other hypergraphs as well. Indeed studying the theta complex of hypergraphs is an interesting problem in its own right.