Here is what I believe is the first example of the le Grand theme by the brothers themselves. The mechanism is simple enough and revolves around the wQ placing extra guard on the squares c4 and c6 while at the same time cutting the bQ or bB lines. There is also has a nice black correction element to the problem.

1.Qe4? (>2.Rc4)
  1...Sf6 (any random move) 2.Rc6
  1...Qxe4 2.Sxe4
  1...Sb4 2.cxb4
  1...Se7!
1.Qe6! (>2.Rc6)
  1...Sf6 2.Rc4
  1...Bxe6 2.Sxe6
  1...Se3 2.Sxd3
  1...Sxb6 2.Bxb6

There are some flaws in the matrix. For one, the duals after 1...Sxb6 and 1...Se3 in the try and dual after 1...Sb4 after the key. I guess these are forgivable in this correction scheme though.

Here is a classic le Grand featuring changed play. The mechanism uses a common means of a line opening of an ambushed piece.  Notice the wBc8 has a masked guard on f5 and g4: this is the essence of the mechanism.

1.Rg5? (>2.Qf5)
  1...Rxa7 2.Rg4
  1...Bg3 2.Qf2
  1...Sd4 2.Qc1
  1...Se3 2.Qxe3 
  1...Sxg5 2.Qxg5
  1...Bxe4!

1.Qh5 (>2.Rg4)
  1...Rxa7 2.Qf5
  1...Bg3 2.Rf3
  1...Sd4 2.e3
  1...Se3 2.Bxe3

The try has a little bit more play but four changed mates in addition to the le Grand is excellent!

Here is one of my more complex affairs.  The problem is pseudo le Grand, meaning the reciprocal change of threat/variation occurs after different defenses.  However, the point of this problem lies in the additional content of white correction, Barnes theme, and the threat avoidance.  

1.Sc2? (random move) 2.Qd4,Qxh1
  1...Qxf6!

1.Sf5? (>2.Qxh1 {Qd4?})
  1...Bf3 2.Qd4
  1...exf5 2.Qd5
  1...Qxf6 2.Sxd6
  1...Sxf5 2.Bb7
  1...Bg2!

​1.Sb5! (>2.Qd4 {Qxh1?})
  1...Sd3 2.Qxh1
  1...e5 2.Qd5
  1...Qxf6 2.Sxd6
  1...Sxb5 2.Bb7
  1...Sb3 2.Qc2
  1...Bb6 2.Sxc3

A random move of the wSd4 creates a double threat of Qd4,Qxh1. However, White must  compensate for the defense 1...Qxd6. To do so the wS must cut the line of either the wRf6 or the wBa6.  In turn, this reduces the double threat because the wQ must keep guard on d3 or f3 in her threatened mate.  The avoided threats reappear after self-blocks. Overall I was pleased with the matrix, but there are quite a few black duals (e.g. 1...Sb3,Se2 2.Qc2 and 1...Sxb5,Sf5 2.Bb7) which detract.  No white pawns!

The le Grand theme in-itself has little room for originality. This problem shows an exciting combination with two different reversals: the le Grand which is a reversal of threat and variation and the reversal 1 which is a reversal of first move/variation.  This is also known as the Lender combination.  Here we have a half-battery that makes things happen.  The pattern is the following:

1.A? (>2.X)
  1...a 2.Y
  1...b 2.B
1.B! (>2.Y)
  1...a 2.X
  1...b 2.A

1.Bxe4 A? (>2.Qa3 X)
   1...Kxb4 a 2.Qb2 Y
   1...Qxb4 b 2.Bc1 B
   1...a3 2.Qb3
   1...Qd5!

1.Bc1 B (>2.Qb2 Y)
  1...Kxb4 a 2.Qa3 Y
  1...Qxb4 b 2.Bxe4 A  
  1...a3 2.Qb3

This is known as a king's le Grand because the le Grand happens after a bK flight.

These last two problems are taken from David Shire's article on the le Grand in the March 2011 issue of the Problemist Supplement.  In this problem the out-of-play wRb6 makes two relevant tries showing the le Grand theme.

1.Rd6? (>2.Rc3)
  1...Sxd4 2.Ba6
  1...Rg8!
1.Re6? (>2.Ba6)
  1...Sxd4 2.Rc3
  1...Se5!

The author has put a new spin on the idea and now the threaten mates reappear as variations in the actual play with a beautiful flight giving key.

1.Se2! (>2.Sxf4)
  1...Sh3 2.Rc3
  1...Kxe2 2.Ba6
  1...Bxe2 2.Rxb3
  1...Rg4 2.Qxf3

​Excellent construction.

Here is a recent le Grand by one of the top contemporary composers. There are some nice changes and battery play combined with the le Grand.  In addition the problem shows the Ellerman-Makihovi theme in which a set dual is separated between try and key.

1...Ke5 2.Sxd6,Sd3

1.Bc8? (>2.Sxd6)
  1...Ke5 2.Sd3
  1...Qe5 2.Sb7
  1...e5 2.Qd5
  1...Rc7!

1.c3! (>2.Sd3)
  1...Ke5 2.Sxd6
  1...Qe5 2.Se4
  1...e5 2.Qd5
  1...g5+ 2.Sd3 (threat)

The key shows a White Goethardt, in the sense that the bBd2 can be unpinned because of interference. 

Finally we end with an excellent cyclic version of the theme.  The pattern is the following:

1.Try? (>2.A)
  1...a 2.B
1.Try? (>2.B)
  1...a 2.C
1.Key! (>2.C)
  1...a 2.A

1.Rf3? (>2.Rg5)
  1...Bxe4 2.Shg4
  1...Rxg7!
1.Qb3? (>2.Shg4)
  1...Bxe4 2.Sfg4
  1...Bd5!
1.Re3! (>2.Sfg4)
  1...Bxe4 2.Rg5
  1...Bd7 2.Sf7
  1...dxe3 2.Qb2

Here is the first problem (even though it was published after the second problem, it was composed first).  I love the open position that features a mirrored bK.  There is set play that won't full anyone but the most inexperienced solvers: 1...Sf8~ 2.Qxe6, 1...Qd5 2.Qxd5.  However, there is no set mate for 1...QxQ.  While this seems to enable the R+S battery by unpinning the lead piece, it actually does not because the wS is guarding c5.   This gives a hint to the key:

1.Qh5! (>2.Qe2)

So the wQ unpins the bQ. Now the bQ is on the loose and does some damage.  However, the wQ also places guard on c5 enabling the R+S battery.  The play follows:

1...Qb6+ 2.Sc5
1...Qh3+ 2.Sg3
1...Qd7,Qd6 2.S(x)d6
1...Qxe4+ 2.Rxe4
1...Qd5 2.Qxd5
1...Sc5 2.Qxc5
1...Bd1 2.Qb5

Overall, a pleasing problem with a thematic key, cross-checks, and battery play.  However, there is one fly in the ointment: the minor dual after 1...Qg4 2.Qd5/Sd6.  This dual is inevitable and it is not worth adding material or losing variations over it.  Besides, these mates are separated in other variations.  

As with any traditional problem there is always a high risk of anticipation. Barry Barnes commented on my problem that the cross-checks had been shown before, but none that he knew of with such a thematic key.  It turns out there are some problems that use a half-pin to show these batter mates (see this problem yacpdb/26o53).  However, it turns out one does not have to look too far to find a similar problem. 12 years earlier the following problem appeared in the same source.  The excellent step back key sets up similar variations:

1.Qf8! (>2.Qh6)
1...Qxf8+ 2.Sf7
1...Qc2+ 2.Sd3
1...Qe7 2.Sc4
1...Qxe5+ 2.Rxe5
1...d3 2.Qxc5
1...Sd3 2.Re2

It's hard to say which problem is better.  On the one hand all of this problem's mates are in the set play.  On the other hand there is no dual.  However, I probably would rank this problem a little higher due to the two nice tries which show the Barnes theme:
1. Qf6? (>2.Qg5,Qh6) d3!
​1.Qe7 (>2.Qg5) h6!

Here is the second problem that I composed around the same time.  This time I used a R+B battery. The position is even more attractive with no pawns and a mirrored bK again.  All of the play is set and all the wQ must do is position herself to make the threat.

1.Qb7! (>2.Qh7)
1...Qe8+ 2.Bf7
1...Qb7 2.Bxb7
1...Qxd5+ 2.Qxd5
1...Qc4,Qb4 2.Be4
1...Rb4 2.Rc4

The problem is pleasing with three nice battery mates, but there is less play and the key is rather perfunctory and is missing that element of surprise.  Ideally, I wanted to start the wQ at a6 for a nice unpinning key similar to my above problem.  However, if we do this (wQa8>wQa6) then the bR is doing double duty guarding both c3 and b5 and so 1.QxQ cooks.  So I submitted the problem as is and it appeared in the high quality French journal Phenix.

​It occurred to me that there is an amazing simple improvement that improves the key AND adds an extra thematic variation (a fourth unpin of the wB), all while maintaining the aristocrat Meredith status.  The key now unpins the bQ letting her do some damage. The added variation is a fourth unpin of the wB this time an indirect unpin:

1.Qb7! (>2.Qh7)
     1...Sc5 2.Bb3 

With the rest of the play remaining the same.

Here is another pawnless wonder that is quite possibly one of my best.  You will notice the arrangement of the the three pieces that stand between the wB and bK.  At first glance this looks to be a half-battery idea similar to those found in the last blog post.  However, it is not, because the same lead piece moves first in each phase.  Instead what we have is known as the Makihovi theme.  There is a set dual: 1...Bc3 2.Sb6,Se3.  Try and key separate this dual and interchanges the two mates between the phases.

1...Kxd5 2.Qa2,Qb3
1...Bc3 2.Sb6,Se3

1.Rb6? (>2.Qb3)
   1...Bc3 (Bb2) 2.Se3
   1...Kxd5 2.Rf5
   1...Bxb6 2.Sxb6
   1...Sb5 2.Qxb5
   but 1...Rf3!

1.Re3! (>2.Qb3)
   1...Bc3 2.Sb6
   1...Bb2 2.Qd3 
   1...Kxd5 2.Rf6
   1...Bxe3 2.Sxe3

The variations 1...Bc3 2.Sb6, 1...Bb2 2.Qd3 exhibit an idea known as dual avoidance.  Namely, after the key is played if one were to just remove the bB from the board there would be two mates 2.Sb6 and 2.Qd3, i.e., a dual. These two mates come from the fact that moving the bB has two errors: opening unguarding b6 and opening the line of guard from d3 to d5. However the two defenses 1...Bc3 and 1...Bb2 only allow one of these mates. The reason is that even though both of these moves make the two errors, they have a compensating effect that only allows one of the mates.  
 

So what is the improvement?  Despite thinking about this problem for a long time, I was not able to reduce it to the Meredith status: 12 pieces.  That is, I did not think I was able to do so, until I looked at the solution in the July Problemist and it dawned on me that the bR can be moved either to f2 or f5 to get rid of the cook 1.Rxf4!  which was the original reason for the 13th piece bSh3.  I have placed the bR at f2 because this also rids the matrix of the parasitic try 1.Sc1 (>2.Qb3) which was present in the first matrix.  I really wish I would have spotted this before publishing!

Here is another problem that I was able to fiddle with for a possible improvement.  The problem is by the great Spanish composer and inventor of the theme bearing his name.  This particular problem is a traditional fair with battery play and three changed mates after the bK flights:

1...Kf5 2.Qg6
1...Kd3 2.Bxc2
1...Kf3 2.Qxa8

1.Rxc2! (>2.Rc3)
1...Kf5 2.Rb7
1...Kd3 2.Rg2
1...Kf3 2.Qg2
1...Be3 2.Rf2
1...f3 2.Rb4
1...bxc2 2.Bxc2

Lovely battery play and even though it is by-play my favorite mate is white interference mate 2.Rf2.  

One thing that bothers me about the Salazar is the wRa3.  Sure, this rook does pull its weight in both the set and actual play. But it is an expensive luxury.  One thought is to just remove it and bPb3, but then 1.Bxc2+ cooks.  However, with some adjustment one arrives at the following matrix.  Is it worth it?  The extra wR is removed, but now the set mate for 1...Kf3 is lost and this flight is unprovided.  

Here I am up to my old tricks.  One of my favorite ideas is the changed check in which White gives up a set check by exploiting a pin. In this problem the idea is coupled with promotion play.  There are some nice tries  by unpinning the lead battery piece, but the key requires something more subtle.

1...Qxf7+ 2.Bxf7

1.Ka6? (K~) (>2.f8=S)
  1...Qf8!

1.Sb5? >2.Sc7
  1...Bf4!

1.Se8! (>2.Sc7)
  1...Qxf7+ 2.Sc7
  1...Qg3 2.f8=S
  1...Qe5 2.f8=Q
  1...Qxg8 2.fxg8=Q
  1...Bf4 2.Sxg7

Here is a perfect example with a half-battery by the master of the 7th rank.  

1.exf7? (>2.f8=Q)
  1...Bg6 2.g8=S
  1...Bg8 2.fxg8=S
  1...Qg4 2.dxe7
  1...Qd5!

1.dxe7! (>2.e8=S)
  1...Qd8+ 2.exd8Q
  1...Bxf5 2.g8=S
  1...Qg4 2.exf7
  1...Qd7 2.fxd7
  1...fxe6 2.Qxe6

Three different promotions in each phase, the best play saved for last with two battery mates, and reversal of key and variation after the defense 1...Qg4.  Yes please.

The famous Bettman task of 6 promotions.

1.Rd7! (>2.c8=Q,cxb8=S,cxd8=S)
   1...Kc8 2.cxd8=Q
   1...Kxa7 2.c8=S
   1...Sxc6 2.cxb8=Q
   1...Kxc6 2.cxb8=S
   1...Se6 2.c8=Q
​   1...Rc8 2.cxd8=S

Lovely promotion play in a miniature. Excellent changes from set play and a wonderful flight giving key. Doesn't get much better than this in a miniature. 

1...Rf8+ 2.gxf8=Q
1...Rxg7 2.Rh8

1.Rg6! (>2.Rh8)
   1...Rxg7 2.Rgxg7
   1...Rf8+ 2.gxf8=S
   1...Kxg7 2.g8=Q

Who doesn't love the promotion mate on the initial bK square!

Here is a problem that was in a recent tourney which I took part in.  I really thought it was excellent total change composition. The choice between a wQ or wS promotion with change of 4 mates.  It's nice that the weaker piece, the knight, wins out.

1.e8=Q (-)
  1...Rxc3 2.Rxd5
  1...Sh~ 2.Qf5
  1...g6 2.Qh8
  1...cxb6 2.Qb8
  1...Rd4 2.cxd4
  1...Bg1!

1.e8=S (-)
  1...Rxc3 2.Bxc3
  1...Sh~ 2.Qe4
  1...g6 2.Qf6
  1...cxb6 2.Bd6
  1...Rd4 2.cxd4
  1...Bg1 2.Qxg3

Here is a light problem with the Fleck theme.

1.e7! (>2.exd8=Q,S,exf8=Q,S)
  1...Rd~ 2.exf8=Q
  1...Rf~ 2.exd8=Q
  1...Rxb8 2.exf8=S
  1...Rxg8 2.exd8=S
  1...Rc8+ 2.bxc8=Q

Finally we end with a masterpiece.  Analogous to the Bettman problem above it shows 6 promotions of a single pawn.  The motivations for the promotions are similar, but this one is so much better. Completely accurate with a flight giving zugzwang key, a changed mate, and an extra promotion mate for good measure.  

1...Kf8 Rxf7

1.exf7! (-)
  1...Kf8 2.fxg8=Q
  1...Kf6 2.fxe8=S
  1...Kxd7 2.f8=S
  1...d5 2.fxe8=Q
  1...Bh7 2.f8=Q
  1...Rf8 2.fxg8=S
  1...Rxd8+ 2.cxd8=Q
  1...S~ 2.Qxd6
​  1...Bxf7 2.Rxf7