[<*[<*x,y*>,'&'],[<*y,c*>,'&'],[<*c,x*>,'&']*>,or3] in InnerVertices (1GateCircStr (<*[<*x,y*>,'&'],[<*y,c*>,'&'],[<*c,x*>,'&']*>,or3))
by Th47;
hence
[<*[<*x,y*>,'&'],[<*y,c*>,'&'],[<*c,x*>,'&']*>,or3] is Element of InnerVertices (MajorityStr (x,y,c))
by Th21; verum