adjacency matrix tip

Library/tips.json

 {"tips":[
+"For any adjacency matrix <i>A</i>, the number of k-cycles in the graph is counted by tr(<i>A<sup>k</sup></i>).",
 "The name of the Nabla (∇) symbol comes, by reason of its shape, from the Hellenistic Greek word νάβλα for a Phoenician harp.",
 "Hurwitz surfaces are compact Riemann surfaces with exactly 84(g-1) automorphisms where g is the genus of the surface.",
 "Regular tetrahedra do not tile <i>R<sup>3</sup></i>.",