these diagrams are ubiquitous - it's funny they are the same diagrams in both electrical engineering and theoretical physics e.g. Topological Quantum Field The

these diagrams are ubiquitous - it's funny they are the same diagrams in both electrical engineering and theoretical physics e.g. Topological Quantum Field Theory http://tex.stackexchange.com/questions/17031/topological-quantum-field-theory-diagrams-with-pstricks-or-tikz http://tex.stackexchange.com/questions/17031/topological-qua...