Tries: 1.a8=Q? but 1...h1=Q! 1.Bxh2? but 1...Kb2! (not 1…bxa3) 1.Sf2? but 1...bxa3! Key: 1.Sc5! (thr. 2.Sd3#) bxa3 2.a8=Q (thr. 3.Qh1#) Kb1 3.Qxa3 (thr. 4.Qa1/Qb2#) c1=Q 4.Qa1+ Kc2 5.Bf5# 3...c1=S+ 4.Kd2 (thr. 5.Qa1/Qb2#) Sxb3+ 5.Qxb3# 4...Sd3 5.Qa1# 4...Sa2 5.Bf5/Qb2# (dual!).
Delayed promotion: An immediate promotion is met by immediate promotion. And to mate, black must be allowed an alternate promotion. Meredith.
