claim: A Backing vocalist's responsibility includes singing with the lead vocalist.
evidence: In algebraic geometry , a White surface is one of the rational surfaces in Pn studied by , generalizing cubic surfaces and Bordiga surfaces , which are the cases n = 3 or 4 .. algebraic geometry. algebraic geometry. A White surface in Pn is given by the embedding of P2 blown up in n -LRB- n + 1 -RRB-  /  2 points by the linear system of degree n curves through these points .. blown up. blowing up