let L be transitive antisymmetric with_infima RelStr ; :: thesis: for a, b, c being Element of L st c <= a "/\" b holds
c <= a
let a, b, c be Element of L; :: thesis: ( c <= a "/\" b implies c <= a )
assume A1: c <= a "/\" b ; :: thesis: c <= a
a "/\" b <= a by YELLOW_0:23;
hence c <= a by A1, YELLOW_0:def 2; :: thesis: verum