## Retrograde problems

### Re: Retrograde problems

Of course Ildjarn.ildjarn wrote:Sorry, I haven't been able to find anything. Can you give the exact last move (capture over which pieces exactly)?

As I suspected a retrograde problem with more then 3 plies may be quite difficult.

Here the first problem needs 4 plies which are very difficult to find.

Position before the last move:

It remains 3 plies to find, for a final score = 040703

The second problem needs 5 plies but, surprisingly, I feel it is far easier than the first problem.

Gérard

### Re: Retrograde problems

I was constantly starting with 9x24 3x19, I just never got the idea for a king on the 46-23 line.

Lasst die Maschinen verhungern, Ihr Narren...

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

### Re: Retrograde problems

Oops you are now very good on 3 plies problem!ildjarn wrote:

I was constantly starting with 9x24 3x19, I just never got the idea for a king on the 46-23 line.

here is the score of this problem

**Spoiler:**

Gérard

### Re: Retrograde problems

Apart from 'last move is probably by piece 32 or 14', I haven't got a clue how to start....

Lasst die Maschinen verhungern, Ihr Narren...

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

### Re: Retrograde problems

Yes Ildjarn, the last move is done by 32 or 14 but one of this two pieces is obviously far better than the other!ildjarn wrote:Apart from 'last move is probably by piece 32 or 14', I haven't got a clue how to start....

The key idea:

**Spoiler:**

Gérard

### Re: Retrograde problems

13-19 32-28 26-31 42x39 45x32

Lasst die Maschinen verhungern, Ihr Narren...

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

### Re: Retrograde problems

Congratulations for having solved this 5 plies problem!ildjarn wrote:

13-19 32-28 26-31 42x39 45x32

Before showing you other problems I would like to discuss with you the criterias I used here to find the best solution.

The idea is to find a solution as simple as possible and I took for grant that the number of plies was the best criteria for measuring the simplicity of a solution.

After having seen your different proposals I am now not quite sure it is the correct approach.

First example:

In order to limit as far as possible the number of plies we have seen the following solution:

but if you search the solution with the minimum number of pieces you find your proposal

which appear to me far simpler!

Second example:

In order to limit as far as possible the number of plies we have seen the following solution:

but you search to find the solution with the minimum number of pieces you find the solution

which appear also simpler with only 4 pieces added instead of 6.

What is your feeling?

Isn't it better to define the priorities as follows:

from the highest priority to the lowest:

1) the number of pieces added is minimum

2) the number of kings added is minimum

3) the number of plies used is minimum

Note: for the two last problems I proposed the solution is the same (they do not depend of the order of priorities).

Gérard

### Re: Retrograde problems

This time I would like to propose some problems by adding the following contraint :

Two problems for beginners (2 plies):

Diag 1

Diag 2

Three rather easy problems (3 plies)

Diag 3

Diag 4

Diag 5

Four difficult problems (5 or 6 plies)

Diag 6

Diag 7

Diag 8

Diag 9

One very difficult problem (10 plies)

Diag 10

Take pleasure studiing such problems !

**you are not allowed to use kings**!Two problems for beginners (2 plies):

Diag 1

Diag 2

Three rather easy problems (3 plies)

Diag 3

Diag 4

Diag 5

Four difficult problems (5 or 6 plies)

Diag 6

Diag 7

Diag 8

Diag 9

One very difficult problem (10 plies)

Diag 10

Take pleasure studiing such problems !

Gérard

### Re: Retrograde problems

Attempts for the first 5 ones:

**Spoiler:**

Lasst die Maschinen verhungern, Ihr Narren...

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

### Re: Retrograde problems

Fine Ildjarn, three optimum solutionsildjarn wrote:Attempts for the first 5 ones:Spoiler:

**Spoiler:**

Gérard

### Re: Retrograde problems

**Spoiler:**

Lasst die Maschinen verhungern, Ihr Narren...

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

### Re: Retrograde problems

**Spoiler:**

Lasst die Maschinen verhungern, Ihr Narren...

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

### Re: Retrograde problems

Here again very good.ildjarn wrote:Spoiler:

The first 5 diag are solved.

Gérard

### Re: Retrograde problems

#7, first attempt:

**Spoiler:**

Lasst die Maschinen verhungern, Ihr Narren...

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!

Lasst sie verrecken!

Schlagt sie tot -- die Maschinen!