[Retros] 10 improved Type A first move economy records

[andrew buchanan]

Dear chess friends,
I have been looking with others at the Type A First Move economy records which Werner Keym publicized in his book Eigenartige Schachprobleme. Here are 6 suggested improvements, 2 corrections, and 2 new versions. These are mostly checked by Mario Richter & his robot friend, Rawbats. I've contacted original authors where possible.
{P01}https://www.janko.at/Retros/d.php?ff=5nkn/3pprPb/1p2prp1/5p2/8/P7/1PPPPPP1/2BQ1K2(11+12) First move of wKf1? WK+AB
[KxD supersedes Werner Keym P1108953]

{P02}
https://www.janko.at/Retros/d.php?ff=4bnkn/3prqPb/4ppp1/5p2/8/P7/1PPPQPP1/2B1KB2(11+12) First move of wQe2? WD+AB
[DxT supersedes Wolfgang Dittmann P0007811]

{P03}
https://www.janko.at/Retros/d.php?ff=7B/6pP/B5Nk/7P/6K1/5PRP/PP4Pp/8(12+3) First move of wBa6? MC+AB
[LxB supersedes Michel Caillaud P1322432]

{P04}
https://www.janko.at/Retros/d.php?ff=B7/1p6/P7/PP6/1BN5/P2N4/P1K5/kB6(11+2) First move of wPa3? MO+AB
[BxT supersedes Markus Ott P1322433]

{P05}
https://www.janko.at/Retros/d.php?ff=8/Pp6/kP6/P1K5/PB6/PN6/P7/8(9+2) First move of wPa3? MO+AB
[BxS supersedes Markus Ott P1322434]

{P06}
https://www.janko.at/Retros/d.php?ff=4BQ1b/3ppK1k/5ppp/8/8/8/8/8(3+7) First move of wQf8? TW+AB
[UD0 supersedes Theophilus Willcocks P0000980]

{P07}
https://www.janko.at/Retros/d.php?ff=BB1nQ1br/p1PP1P1p/1ppKpkPP/5prp/6p1/8/8/8(9+13) First move of wDe8? MC+HJ
[UDxS corrects P1322438]

{P08}
https://www.janko.at/Retros/d.php?ff=n7/Bpp1p2p/1p4pP/PK6/p7/1kP5/1pRP4/Qnb5(8+12) First move of wBa7? MC+HJ+MR+AB
[ULxT corrects P1322504]

{P09}
https://www.janko.at/Retros/d.php?ff=8/8/8/8/5P1P/4PPBR/1PPkPrBr/2brb1K1(11+6) First move of wLg2? MC
[ULxL version P1322430]

{P10}
https://www.janko.at/Retros/d.php?ff=K2nb3/Nn1krp2/rPbrp3/pppp4/8/8/8/8(3+14) First move of wSa7? MC
[USxL version P1322515]

To see all 55 compositions of this form in PDB, go tohttps://pdb.dieschwalbe.de and search for:k='first' and k='econ' and k='type a'
The theme asks to show the *first* move of a particular piece. There are 6 types of piece, and 7 kinds of move to be shown ("never moved", "moved without capture", "captured specific piece type"). Also, promoted pieces are considered to be reborn, so one can ask, for each of the 4 types of promoted piece, for the 7 kinds of move. There are also 4 special moves (double pawn hop, 0-0, 0-0-0, and e.p.). This gives (6+4)*7+4 = 74 candidates. However, all knight moves and all but two rook moves are impossible to prove as first moves, and e.p. is clearly not a first move. This leaves 74-7-5-1 = 61 real tasks. Three of Bernd Schwarzkopf's problems embed multiple simple tasks, so all 61 tasks are exhibited in the 55 compositions.
Michel Caillaud was the real master of this subgenre, showing a wealth of ingenious mechanisms, and not necessarily prioritizing economy. The final hold-out (KxS) was found by Gerd Wilts, and is very satisfying. There hasn't been any movement in this space for many years, and yet I am sure there is further scope for improvement. These come under the usual objective priority list for such economy problems:
(1) minimize number of units, then
(2) minimize number of officers,
(3) minimize number of major officers,
(4) minimize number of queens,
If still equal, these are considered to be ex-aequo.
My personal preference with all economy records after applying these 4 criteria is additionally to minimize the number of non-standard officers (with bishops of different parity taken to be distinct types). Non-standard material is great, but can only appear if essential.

The stipulations are not uniform. Some refer to a piece by its diagram location, some refer to a piece's game array location, and some are more open-ended. I don't want to fiddle around with prior work, but for me, a canonical stipulation would always refer to the piece by its diagram location, unless it has been captured, in which case it would refer to its starting square (either game array or promotion square).

Werner Keym also recommends us to explore Type C problems of this form, where there are many gaps to be filled.
Comments welcome.

Thanks,
Andrew
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