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MatPlus.Net Forum General What is this theme, if any?
 
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(1) Posted by Oliver Petrov [Sunday, Sep 26, 2010 11:24]

What is this theme, if any?


1.X? Threat A#, but 1..a!
1.Y? Threat A#, but 1..a!
solution:
1.Z! 1..a -->B#
 
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(2) Posted by seetharaman kalyan [Sunday, Sep 26, 2010 14:39]

what is special about this pattern (??) that it should be a theme?
 
 
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(3) Posted by Oliver Petrov [Sunday, Sep 26, 2010 15:17]

IMHO the special thing is that the refuting move 1..a! becomes necessary move after the key. But I am not very advanced composer.
 
   
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(4) Posted by Sarah Hornecker [Sunday, Sep 26, 2010 22:34]

Changed Mate
 
   
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(5) Posted by Dmitri Turevski [Monday, Sep 27, 2010 14:18]

In what sense is it changed?
 
   
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(6) Posted by Oliver Petrov [Monday, Sep 27, 2010 14:35]

Siegfried, with my respect to your experience, but note that 1...a! is the refuting defense after which there is no mate, not a defense to the try move after which there is a mate "to change" in the actual play. Is my remark founded?
 
   
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(7) Posted by Georgy Evseev [Tuesday, Sep 28, 2010 09:55]

To start with, the content of a problem (even twomover) is often may not be described by a simple matrix. There some great problems that are not interesting at all if only a matrix is shown. But in this case there is only matrix to comment on.

Generally, in multi-phase twomover it is interesting when we have a pattern, but not a repetition. From this point of view, the first two phases are too repetitive and redundant. So, the phase 1.Y? does not add anything to the matrix (but may well add something to the contents of problem))).

In the remaining two phases there is only one common element which may be the part of the pattern - black move 1..a. It is used as a refutation in one phase and as a defence in other phase.

This puts this matrix in a wide group of themes called "change of functions of moves". There is nothing more to say about this matrix, but in this group of themes it preferrable when white (and not black) moves change their functions.
 
 
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(8) Posted by Nikola Predrag [Wednesday, Sep 29, 2010 06:56]; edited by Nikola Predrag [10-09-29]

1.X? Threat A#, but 1..a!
1.Y? Threat A#, but 1..a!
solution:
1.Z! 1..a -->B#
It is almost a description of any direct problem - White threats and Black defends, so the solution must provide a new mate after defence of some threat. Multiplying the tries with the same threat and defence, does not multiply the content. But a composer may test his constructional skills by searching for maximal number of such tries. If some other composers accept the challenge and start to compete, it may become a task-theme.
example
(= 3+2 )
#2vvvvvv
1.B~? (2.Ra1#); 1... e2! (=6 tries)
1.Bd4! ~,e2 2.Ra1,Rh8 #
Moving R/B to b8/b2 we get 7 tries (or 8, by moving R/B to c8/c3), with the same threat and refutation.

Several tries with the same threat may be interesting if there are several (different) respective defences. Or, the same defensive move may have different defensive motifs. To make a theme of it you need a construction that clearly shows it.
example
(= 7+7 )
#2vv(vv)
1.Qf8?(X) ~ 2.Re4#(A); 1... Sd6!(a1)->(2.Re4+ Sdxe4)
1.Qb8?(Y) ~ 2.Re4#(A); 1... Sd6!(a2)->(2.Re4+ Sfxe4)
- 1. f3 ! (Z) ~ 2.Rf5#(B) ; 1.... Sd6 (a3)->(2.Rf5 + Sxf5 ) 2.e3#(C); 1... Sxg4 2.Re4#(A)
{1.Qe8? ~,Sxe8 2.Rf5#(B),Re4#(A); 1... Sd6!(a3)->(2.Rf5+ Sxf5)}
{1.Qc8? ~, Sd7 2.Qf5#(C),Re4#(A); 1... Sd6!(a3)->(2.Rf5+ Sxf5)}
But a good problem needs more than just beeing formally thematic.
 
 
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(9) Posted by Sarah Hornecker [Wednesday, Sep 29, 2010 07:53]

Yes, my apologies. Of course I am not a twomover expert and easily confuse things. Nikola's reply is correct, mine was wrong.
 
   
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(10) Posted by Oliver Petrov [Wednesday, Sep 29, 2010 09:00]; edited by Oliver Petrov [10-09-29]

Don't worry
 
 
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MatPlus.Net Forum General What is this theme, if any?