I am new to matrix, can anyone explain what are these symbols mean? Especially the 2nd half of the portion, while I can read from description for the first part.

PageRank with Restart: Matrix Let G = (V, E) (web graph) be a directed graph, with V = {v1, ..., Vn} Let din(v) be the in-degree of v, i.e. Oin(v) = Ku : (u, v) E E} , while let dout (v) be its out-degree, i.e. Sout (v) = Hu : (v, u) E E}. Let Mc (M for short) be a n x n matrix with entries in [0, 1] as follows: I H if ( vj , vi ) E E Mij = Bout ( V;) if ( v; , vi) $ E ' [u 'T]a!'!A