theorem Th1: :: GLPACY00:1

for G1 being _Graph
for G2 being Subgraph of G1
for v1 being Vertex of G1
for v2 being Vertex of G2 st v1 = v2 holds
( v2 .inDegree() c= v1 .inDegree() & v2 .outDegree() c= v1 .outDegree() & v2 .degree() c= v1 .degree() )