Reciprocal change is a difficult and paradoxical idea in chess composition. It happens when two mates are interchanged between the same two defenses between two phases. In algebraic terms: In one phase mate A follows defense X while mate B follows defense Y. In another phase mate B follows X and mate A is switched to defense Y. Even though I have not had much success at it, reciprocal change is one of my favorite themes. We begin with a crystal clear example by Barry Barnes.
In general two-movers with multiple solutions are not considered to be sound problems. However, sometimes multiple solution problems can be composed intentionally with wonderful effects. Here are some of my favorites.
On the side I like to dabble in chess problem composition. I am mostly interested in two and three move direct mates. I hope to convey the beauty and logic of chess problems with this blog. In the entries are some of my favorite problems and my own problems. Before looking at the problems I suggest reading this introduction to the chess problem world by the British Chess Problem Society. Also, here is a list of terminology and themes. Here is a link to my problems on yacpdb.
1. "Choose wisely" The Problemist Supplement, Sept. 2016
2. "Double checking white in a two mover" StrateGems July 2016
3. "Double check without capture" The Problemist Supplement, January 2018
4. "The disappearing Nowotny: Part I" The Problemist Supplement, March 2018
5. "The disappearing Nowotny: Part II" The Problemist Supplement, May 2018
6. "The disappearing Nowotny: Part III" The Problemist Supplement, July 2018
7. "Castling with half-battery and Fleck themes" StrateGems, July 2018
8. "The Baku Nowotny" StrateGems, January 2019
9. "The Romanian Nowotny with Fleck" The Problemist, March 2019
10. "Mirror Image" The Problemist Supplement, May 2019
11. "White King in Check" Problemas, July 2019
12. "A Simple Mechanism", StrateGems, July 2019
13. "Miniatures with castling and (partial) Fleck" Problemist Supplement, September 2019
14. "Taking the Straitjacket off the Fleck" The Problemist Supplement, November 2019
15. "Unforced threats" The Problemist Supplement, May 2020
16. "Ojanen in Miniature" The Problemist Supplement, May 2020
17. "Developments in the Finnish Nowotny" The Problemist, July 2020
18. "Categorising the Fleck theme" The Problemist, January 2021
19. "Masking the Bristol" The Problemist Supplement, March 2021
20. "My love of the Novotny" StrateGems July 2021
21. "Masked Novotny" The Problemist Supplement, November 2021