Nº51 Jorge Kapros

H#4 (9+6) C+

1.Sxc3! (Sxa3 ?) Txa4! (Txf6 ?) 2.Sb1 Ta6 3.Sxa3 Txf6 4.Sb1 Ta6#
Theme and comment:
Two switchbacks by a single black unit (Sb1)
+
Two switchbacks by a single white unit (Ta6)
=
Four switchbacks by only 2 units in exactly the necessary 4 moves for the theme, no additional moves.
Dual avoidance because switchbacks must be done in order.
Yes order Sxc3!-Sb1-Sxa3-Sb1 and no changed order Sxa3?-Sb1-Sxc3-Sb1
Yes order Txa4!-Ta6-Txf6-Ta6 and no changed order Txf6?-Ta6-Txa4-Ta6
First realization of the theme of four switchbacks with only 2 thematic units, 1 black unit making two switchbacks and 1 white unit making two switchbacks