Single-inversion criterion: U·(b,c)·V (classes mod 4) has a SAFE extension iff 4c−3b ∉ b·V or 5c−4b ∉ U·c

Initializing...

Single-inversion criterion: U·(b,c)·V (classes mod 4) has a SAFE extension iff 4c−3b ∉ b·V or 5c−4b ∉ U·c · Prove2Me