Leffie: A move is illegal if it leaves a piece paralysed in Eiffel. (introduced in Quartz 46)
Eiffel Chess: Units, other than Kings, are paralysed when they attack each other. The paralysis occurs in the sequence P-N-B-R-Q-P. A Pawn paralyses an enemy Knight; a Knight paralyses an enemy Bishop, and so on. A paralyzed unit loses all powers except that of causing paralysis. Fairy pieces play normal, without paralysis.
Back-home: a) If a piece can legally move to the square it occupied in the initial position of the problem, it must move to this back-home square. b) Back-home moves are prevalent to the virtual capture of the opponent King by any piece, i.e. “checks are fairies”. c) If several back-home moves are legal, the side-on-move chooses which one to play. d) The back-home square of a Pawn which is promoted during the solution is the initial square of this Pawn. See the link https://juliasfairies.com/articles/back-home-fcondition-ndupont/ for more details on the back-home fairy condition.
No.1488Nicolas Dupont France original – 21.03.2020
Come and go castling in a capture-free proof game (maybe a novelty)! The
motivation for the castling is a tempo manoeuver – the dynamic of the game implies that Bh7 must be played as soon as possible (Se5 cannot be played earlier as Bd3 is then illegal and the white side is squeezed), and 3.Se2 4.O-O is the only waiting sequence to achieve this goal. The problem is thematic for the Quartz TT13 but I found it after the deadline - it is C+ Jacobi. (Author)
A fantastic problem! The path of the wBf1 is especially good. There are plenty of Leffie effects, as follows:
2.Ba6?? is illegal because bSb8 would observe wBa6.
The Back-home move 4.Sg1?? is illegal because wQd1 would observe bPh5.
9.Bb5?? is illegal because wBb5 would observe bRa4.
Nikola Predrag
March 23, 2020 19:00
Moves like 2.Ba6?? are simply illegal. It’s not even trivial, it’s just the rules. It seems nonsensical to ask ‘why to choose a legal move instead of an illegal move’.
The point is in choosing AMONG THE LEGAL moves – ‘why this and not that LEGAL move’. A ‘Leffie effect’ makes sense when the illegality is the result of certain MOVE/PLAY, when the particular choice of moves creates such a ‘Leffie effect’.
The problem is fantastic because the intertwined conditions give birth to the new, transcendent features.
2.Bb5 c4 is a critical move & line-closure to prevent the ‘Back home’ 3.Bb5-f1
3.Se2 does the same (but anticipatory, to allow the line-opening 4…c3)
3…h5 pins wS, preventing ‘Back home’ Se2-g1
4.?? is the central point of the idea. White needs an ‘odd tempo’ to allow 4…c3 5.Bd3 (e.g. 4.Sa3? c3 5.Sb1). 4.f3? is ‘odd’ but unpins wS (4…c3 5.Sg1)
4.0-0 is the only good ‘odd’ choice at the moment but in the end it becomes ‘evened’ (4 moves altogether)
5…Rh6 6.Bh7 (critical&line-closure) enables 6…Ra6, which with 7…Ra4 determines (by departure) the timing of 8.Bd3 and the unique arrival 9.Ba6 (9.Bb5 is MADE illegal by the CHOSEN arrival of bR)
11.Rh1!(11.Ke1?/Sg1??) is the unique good choice among 3 ‘Back home’ moves (11.Ke1 leaves no time for ‘Back home’ by wB before 13…b5)
However, why that particular arrival 7…Ra4 is necessary, since 9.Ba6 is needed to prevent ‘Back home’ 9…Sb8 ?
dupont
March 23, 2020 21:06
Thanks friends for your elogious comments. Almost all thematic points have been listed. I played 6…Ra6 to get the opportunity to then play the important waiting move 7.f3 safely. Then 7…Ra5/a4/a3 are possible – I choosed square a4 just because a black rook should stand on a white colored square when possible (for a better visual effect).
This is another little jewel by Nicolas. By the way, he made a collection of such pgs (with Leffie condition) with the occasion of TT13 Quartz, recently judged by V. Crișan. See http://quartz.chessproblems.ca/pdf/49/Quartz49.pdf
No.1488
A fantastic problem! The path of the wBf1 is especially good. There are plenty of Leffie effects, as follows:
2.Ba6?? is illegal because bSb8 would observe wBa6.
The Back-home move 4.Sg1?? is illegal because wQd1 would observe bPh5.
9.Bb5?? is illegal because wBb5 would observe bRa4.
Moves like 2.Ba6?? are simply illegal. It’s not even trivial, it’s just the rules. It seems nonsensical to ask ‘why to choose a legal move instead of an illegal move’.
The point is in choosing AMONG THE LEGAL moves – ‘why this and not that LEGAL move’. A ‘Leffie effect’ makes sense when the illegality is the result of certain MOVE/PLAY, when the particular choice of moves creates such a ‘Leffie effect’.
The problem is fantastic because the intertwined conditions give birth to the new, transcendent features.
2.Bb5 c4 is a critical move & line-closure to prevent the ‘Back home’ 3.Bb5-f1
3.Se2 does the same (but anticipatory, to allow the line-opening 4…c3)
3…h5 pins wS, preventing ‘Back home’ Se2-g1
4.?? is the central point of the idea. White needs an ‘odd tempo’ to allow 4…c3 5.Bd3 (e.g. 4.Sa3? c3 5.Sb1). 4.f3? is ‘odd’ but unpins wS (4…c3 5.Sg1)
4.0-0 is the only good ‘odd’ choice at the moment but in the end it becomes ‘evened’ (4 moves altogether)
5…Rh6 6.Bh7 (critical&line-closure) enables 6…Ra6, which with 7…Ra4 determines (by departure) the timing of 8.Bd3 and the unique arrival 9.Ba6 (9.Bb5 is MADE illegal by the CHOSEN arrival of bR)
11.Rh1!(11.Ke1?/Sg1??) is the unique good choice among 3 ‘Back home’ moves (11.Ke1 leaves no time for ‘Back home’ by wB before 13…b5)
However, why that particular arrival 7…Ra4 is necessary, since 9.Ba6 is needed to prevent ‘Back home’ 9…Sb8 ?
Thanks friends for your elogious comments. Almost all thematic points have been listed. I played 6…Ra6 to get the opportunity to then play the important waiting move 7.f3 safely. Then 7…Ra5/a4/a3 are possible – I choosed square a4 just because a black rook should stand on a white colored square when possible (for a better visual effect).
This is another little jewel by Nicolas. By the way, he made a collection of such pgs (with Leffie condition) with the occasion of TT13 Quartz, recently judged by V. Crișan. See http://quartz.chessproblems.ca/pdf/49/Quartz49.pdf