Proofgold Proof

pf
Let x0 of type ι be given. Let x1 of type ι be given. Assume H0: In x1 (Union x0). Apply unknownprop_99c6830b7507eb1c538c7366f637e956be6dad337531dd2702ca6ba6923a9849 with x0, x1, False. The subproof is completed by applying H0. ■