
theorem Th64: :: AChain0:
for G being SimpleGraph, A being StableSet of G, B being Subset of A
 holds B is StableSet of G
proof
 let R be SimpleGraph, A be StableSet of R, B be Subset of A;
 set VR = Vertices R;
 reconsider BB = B as Subset of VR by XBOOLE_1:1;
 BB is stable by Def19;
 hence thesis;
end;
