[Retros] EQUAL LAST MOVE (ELM) - 10.06.07 Updating

[raosorio at fibertel.com.ar]

Dear friends, 

I'm posting here the ELM updated status. 

I repeat  the complete presentation in order to make the things easier for newcomers.
We are finding that the economy is based on the most clever combination of white and
black restrictions. I think that the PxQ example is a high quality demonstration. I strongly
recomend to see this one.

Bernd has found many improvements on his own previous records, proving that we are going 
through a learning period during which the intrinsic ELM technic has to be discovered.

Dead Reckoning: it's clear that DR could plays a strong rol here. For instance the position
k7/2Kb4/8/8/8/8/8/8 is a 3 pieces KxN record and there are surely many others coming from
the B type (we are missing the specialist here). I'll keep separated the non DR records as
pre-1997 and the DR records as post-1997, as it was done for the D Type .

I'm quite convinced that the ELM e.p. case has chances based on DR.

Bernd found a delicious detail. His RxB is a twin of his R- (replace wP on a3 by a bP).
If we  forget the record approach for a while this could be continued as,

8/8/8/8/1p6/P7/rPP1k3/1RK5
Equal Last move
a) diagram   b) replace wP on a3 by a bP   c) from b), b4 to b3
Solution:  a)  R-  b) RxB  c) RxN

This is an example of ELM potential other than records.

You can send your originals via this RML or via private mail to me (many cases still pending)
Following a Mario's suggestion I included the number of pieces of the Last Move Type DD 
record for each case. This number indicates what to improve since any LMDD problem is an 
ELM too by nature.

Best,
Roberto

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EQUAL LAST MOVE (ELM)- Definition 
Twinning a) white to move, b) black to move. Find the a) and b) "same nature" legal last move. 

The move's nature is determined by the type of the piece/pieces involved (K, Q, R, B, N, P) and 
the type of movement (simple, straight promotion, simple capture, capturing promotion, e.p., 
pawn double step, O-O, O-O-O). 

An ELM problem is not (in general) a Last Move type D one. The diagram could present many legal 
candidates to be the last move, but there is just one for a) and just one for b) that are of 
the same nature. On the contrary, all the Last Move type DD problems are particular ELM ones. 

There are 60 theorical cases (surely 57 in practice due to castlings and e.p. ??)
We are trying here to find the economy records (minimal pieces number). On top of records, 
I think that this stipulation could be used to composse some nice problems with many tries. 

Some examples are a light variation of the previous Type B ones and they are indicated as such.
Dates are reception ones,  i) means improved from  previous updating, and n) means new.

I included the reference of the Last Move Type DD record (Type DD is the particular Type D cases 
where the last move is of the same nature both for WTM and BTM) in the form of DDxx, where xx
is the number of pieces in the corresponding DD record.

For instance, in the following first case the move is K-, after that DD12 indicates that the DD
record uses 12 pieces, and after that (3+2=5) means that the ElM record uses 3 white pieces
and 2 black pieces, total 5. Then, the FEN, author and reception date.

   K- DD12 (3+2=5) (8/8/8/6R1/7k/8/7K/6Rb) Bernd Schwarzkopf/9.05.2007 
   KxQ DD24 (2+11=13) (8/ppppppp1/7p/7R/7K/8/7k/6nn) Bernd Schwarzkopf/9.05.2007 
   KxR DD22 (3+3=6) (bK6/8/bk6/NP6/8/8/8/8) Bernd Schwarzkopf/9.05.2007 
   KxB DD14 (2+3=5) (K1k5/2rp4/2P5/8/8/8/8/8 ) Bernd Schwarzkopf, Werner Keym/9.05.2007 
   KxN DD10 (3+2=5) (K7/8/k7/P7/8/8/7b/6Q1) Bernd Schwarzkopf/9.05.2007 
   KxP DD24 (1+5=6) (8/8/8/1q1r4/k7/n1K5/5q2/8) Bernd Schwarzkopf/9.05.2007 

i) Q-    DD13 (5+4=9) (8/8/8/3k4/8/PP6/qnpP4/1QK5) Bernd Schwarzkopf/08.06.2007
   QxQ DD??              PENDING
   QXR DD??             PENDING
   QXB DD??             PENDING
   QxN DD12 (5+2=7) (8/8/8/8/8/P7/1PP5/qQK1k3) Thierry Le Gleuher /14.05.07
   QXP DD26             PENDING

i) R- DD13    (5+3=8) (8/8/8/8/1p6/P7/rPP1k3/1RK5) Bernd Schwarzkopf/08.06.2007
   RXQ DD17             PENDING
   RXR DD??             PENDING
n)RXB DD18 (4+4=8) (8/8/8/8/1p6/p7/rPP1k3/1RK5) Bernd Schwarzkopf/08.06.2007
n)RXN DD9   (3+4=7) (8/8/8/8/8/np6/rP2k3/1RK5) Bernd Schwarzkopf/08.06.2007
   RXP DD25              PENDING
 
   B- DD12    (7+4=11) (8/8/1p6/b7/8/P2P4/P1kPP3/K1Bb4) Bernd Schwarzkopf/9.05.2007 
   BXQ DD24              PENDING
   BXR DD11              PENDING
   BXB DD27              PENDING
i) BxN DD11 (6+2=8) (8/8/8/8/8/4P1PP/5BPb/4K2k) Bernd Schwarzkopf/06.06.2007
   BXP DD26              PENDING

i) N-    DD11    (5+2=7) (8/8/8/8/8/5K2/4PPPk/6Nn) Bernd Schwarzkopf/08.06.2007
   NxQ DD17 (3+10=13) (1nbk2NR/1p1ppppK/p6p/8/8/8/8/8) B.Schwarzkopf/9.05.2007 (B,Bartolovic, Buljan) 
   NXR DD16             PENDING
n)NXB DD19  ( 2+7=9)  (5KNr/4p1np/4b3/5k1b/8/8/8/8) Roberto Osorio & Jorge Lois/9.06.07
n)NXN DD17  (6+3=9) (8/8/8/8/8/8/kPPP2P1/rNK1n3) Roberto Osorio & Jorge Lois/9.06.07
   NXP  DD25             PENDING

   P-    DD8      (2+2=4) (8/8/8/8/8/6P1/7p/5K1k) Roberto Osorio/20.04.2007 
   P--   DD17   ( 3+3=6) (8/7p/7P/6pK/5k1P/8/8/8) Bernd Schwarzkopf/9.05.2007 
   PxQ DD24   (3+7=10) (8/8/8/8/4N1K1/5P1P/6Pp/4BkNb) Bernd Schwarzkopf/9.05.2007 
   PxR DD21   (7+2=9) (8/8/8/4KR2/7P/7P/6Pp/5BkN) Bernd Schwarzkopf/9.05.2007 
   PxB DD16   (6+2=8) (8/8/8/4KN2/7P/7P/6Pp/6Nk) Bernd Schwarzkopf/9.05.2007 
   PxN DD16   (5+2=7) (8/6K1/7P/8/8/7P/6Pp/6Nk) Bernd Schwarzkopf/9.05.2007 
   PxP DD18   (5+2=7) (8/4K3/8/8/7P/5N1N/6Pp/7k) Bernd Schwarzkopf, Werner Keym/9.05.2007 

   P-=Q DD20 (5+2=7) (7Q/8/8/7P/8/6K1/6P1/5Bkq) Bernd Schwarzkopf/9.05.2007 
   P-=R DD20 (5+2=7) (7R/8/8/8/8/6P1/5K1P/5Brk) Bernd Schwarzkopf/9.05.2007 
   P-=B DD10 (2+3=5) (7B/6p1/8/8/8/7K/8/6bk) Bernd Schwarzkopf/9.05.2007 
   P-=N DD16 (2+4=6) (7N/8/8/8/8/8/5pr1/3k1K1n) Bernd Schwarzkopf/9.05.2007 

   PxQ=Q DD24 (2+12=14) (nQr1n3/1ppKp1p1/kp1pp3/8/8/8/8/7q) Werner Keym/9.05.2007 
   PxQ=R DD23 (2+12=14) (nRr1n3/1ppKp1p1/kp1pp3/8/8/8/8/7r) Werner Keym/9.05.2007 
   PXQ=B DD25             PENDING
   PXQ=N DD24             PENDING

   PXR=Q DD??             PENDING
   PxR=R DD20  (7+2=9)  (7R/5K2/6P1/8/8/1P6/kP6/NrB5) Bernd Schwarzkopf/9.05.2007 
   PxR=B DD24  (2+8=10) (4rnBr/5Kp1/4r3/8/81p6/2k5/b7) Jorge Lois & Roberto Osorio/2.06.07
   PXR=N DD24             PENDING

   PxB=Q DD26   (2+7=9)  (5KQn/4pbn1/8/8/8/1p6/2k5/q7)   Jorge Lois & Roberto Osorio/2.06.07
   PxB=R DD16   (5+2=7) (R7/2K5/1R6/8/8/P7/k7/rR6) Bernd Schwarzkopf/9.05.2007 
   PxB=B DD25   (2+7=9) (5KBn/4pbn1/8/8/8/1p6/2k5/b7) Jorge Lois & Roberto Osorio/2.06.07
   PXB=N  DD16            PENDING

   PxN=Q DD23  (2+6=8) (KQn5/1pp5/kp6/8/8/8/8/q7) B.Schwarzkopf/9.05.2007 (Type B,many authors) 
   PxN=R DD14  (4+2=6) (1R6/2K5/8/8/8/P7/k7/rR6) Bernd Schwarzkopf/9.05.2007 
   PxN=B DD24  (2+7=9) (5bBn/6pK/4p3/7k/8/8/8/6nb) Jorge Lois & Roberto Osorio/2.06.07
   PxN=N DD22  (2+5=7) (6KN/5r1r/6n1/8/8/8/2k5/1n6) Jorge Lois & Roberto Osorio/2.06.07