reserve x,y,c for set;

theorem Th1:
  InnerVertices BorrowStr(x,y,c) is Relation
proof
  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_1:3,38;
  then
  InnerVertices 1GateCircStr(<*[<*x,y*>, and2a], [<*y,c*>, and2], [<*x,c*>
  , and2a]*>, or3) is Relation & InnerVertices BorrowIStr(x,y,c) is Relation
by FACIRC_1:3,38;
  hence thesis by FACIRC_1:3;
end;
