let x, y, c be set ; :: thesis: InnerVertices (BorrowStr (x,y,c)) is Relation
( InnerVertices (1GateCircStr (<*x,y*>,and2a)) is Relation & InnerVertices (1GateCircStr (<*y,c*>,and2)) is Relation ) by FACIRC_1:38;
then ( InnerVertices (1GateCircStr (<*x,c*>,and2a)) is Relation & InnerVertices ((1GateCircStr (<*x,y*>,and2a)) +* (1GateCircStr (<*y,c*>,and2))) is Relation ) by FACIRC_1:3, FACIRC_1:38;
then ( InnerVertices (1GateCircStr (<*[<*x,y*>,and2a],[<*y,c*>,and2],[<*x,c*>,and2a]*>,or3)) is Relation & InnerVertices (BorrowIStr (x,y,c)) is Relation ) by FACIRC_1:3, FACIRC_1:38;
hence InnerVertices (BorrowStr (x,y,c)) is Relation by FACIRC_1:3; :: thesis: verum