let x be Point of ; :: thesis: ( x <= 1 / 2 implies 2 * x is Point of )
assume x <= 1 / 2 ; :: thesis: 2 * x is Point of
then A1: 2 * x <= 2 * (1 / 2) by XREAL_1:66;
0 <= x by BORSUK_1:86;
hence 2 * x is Point of by A1, BORSUK_1:86; :: thesis: verum