a) 1.a6! zz. Kh2 a 2.a7 A zz. Kh1 3.a8Q+ Kh2 4.Qg2#;

b) 1.a7! A (~ 2.a8Q+ Kh2 3.Qg2#) Kh2 a 2.a8R B Kh1 3.Ra3 Kh2 4.Rh3#.

Change of continuation and different promotions in a miniature.

a) 1.Ba.5-a6 Kh1-h2 2.Ba6-a7 Kh2-h1 3.a7-a8D Kh1-h2 4.Da8-g2#

b) Pa5->a6 (After key)

b) 1.Ba6-a7 Kh1-h2 2.a7-a8T Kh2-h1 3.Ta8-a3 Kh1-h2 4.Ta3-h3#