Sergey, you can add (at the minimum)
e) Rh1->f3
1…e4 2.e5 Bc4 3.Se7 Bxf7‡
the “famous square” f7!!
I take a lot of fun to search other twins.
Thank you !
Again another twin !
g) g7->g4
1…Sc3 2.e5 Se4 3.Se7 Sf6‡
Luce Sebastien
February 26, 2018 00:05
One interesting info :
In club the mate of a) is named “Marmelade Mate” !
The explanation is that after the moves 1.e4 e5 2.Dh5, the player with white says “Oh but you have marmelade on your King e8 !” So the player with black touches his King to verify… And white says “You touched the King, you have to play it !”
So the end…
Andrew Buchanan
February 27, 2018 02:12
In b) might instead have history 1. Sh3 f5 2. Sf4 Kf7 and then both officers go home, bK triangulating. There’s another one with 1. Sc3 f6 2. Sd5 f5 3. Sf4 and now bS or bK make an even number of moves while wS returns home. I guess there is a kind of PRA here where you need to find a forward solution for each possible kind of retro history. Ronald Turnbull would love it. Does Jacobi allow for assignment of initial state? (A kind of move 0 as was done with Chess960.)
No.1280
Very funny! I would like my opponents play like that in classical games of chess ! Congratulations Sergey ! 🙂 luceechecs@gmail.com
For position b) the only possible proof games are 1.Sa3/Sc3/Sf3/Sh3 f6 2.Sb1/Sg1 f5, so the solution must start with a wS move followed by bPf5-f4.
Thank You
Sergey, you can add (at the minimum)
e) Rh1->f3
1…e4 2.e5 Bc4 3.Se7 Bxf7‡
the “famous square” f7!!
I take a lot of fun to search other twins.
Thank you !
e) Rh1->f3 is, however, illegal position.
Another twin !
f) f7->h5
1…c4 2.c5 Qc2 3.h6 Qg6‡
Again another twin !
g) g7->g4
1…Sc3 2.e5 Se4 3.Se7 Sf6‡
One interesting info :
In club the mate of a) is named “Marmelade Mate” !
The explanation is that after the moves 1.e4 e5 2.Dh5, the player with white says “Oh but you have marmelade on your King e8 !” So the player with black touches his King to verify… And white says “You touched the King, you have to play it !”
So the end…
In b) might instead have history 1. Sh3 f5 2. Sf4 Kf7 and then both officers go home, bK triangulating. There’s another one with 1. Sc3 f6 2. Sd5 f5 3. Sf4 and now bS or bK make an even number of moves while wS returns home. I guess there is a kind of PRA here where you need to find a forward solution for each possible kind of retro history. Ronald Turnbull would love it. Does Jacobi allow for assignment of initial state? (A kind of move 0 as was done with Chess960.)