let a, b be Real; :: thesis: ( 1 <= a & 1 <= b implies 1 <= a * b )
assume that
A1: a >= 1 and
A2: b >= 1 ; :: thesis: 1 <= a * b
a * b >= b * 1 by A1, A2, Lm12;
hence 1 <= a * b by A2, XXREAL_0:2; :: thesis: verum