let E be set ; :: thesis: for A, B being Subset of E holds A ` c= (A /\ B) `
let A, B be Subset of E; :: thesis: A ` c= (A /\ B) `
A /\ B c= A by XBOOLE_1:17;
hence A ` c= (A /\ B) ` by Th31; :: thesis: verum