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MatPlus.Net Forum General A fishy Belen
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(1) Posted by Rewan Demontay (Real Name: James Malcom) [Wednesday, Sep 23, 2020 07:24]

A fishy Belen

Here's a light snack for all of you to solve. -)

Mate In 4

(= 13+1 )


EDIT: I have changed the diagram due to posting the wrong one. However, here is the original one or convenience though.
(= 11+1 )

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(2) Posted by Hauke Reddmann [Wednesday, Sep 23, 2020 09:00]

Hint to all solvers: Be aware what
automatic preconditions your
solving programm assumes -
including move numbering :-)
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(3) Posted by Andrew Buchanan [Wednesday, Sep 23, 2020 16:37]

(= 10+1 )
My version of James' Belen. More or less fishy?
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(4) Posted by Jakob Leck [Wednesday, Sep 23, 2020 21:26]

"More or less fishy?"

I would say less fishy because there actually is a (non-thematic) solution.
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(5) Posted by Hauke Reddmann [Wednesday, Sep 23, 2020 22:43]

Uhm, which solution? :-)
You all outfished yourselves as the Kc2 can't
have gotten there without kicking the Ke1.
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(6) Posted by Jakob Leck [Wednesday, Sep 23, 2020 23:09]

Exactly, Hauke, this is why it is fishy. But Andrew's position is solved by 1.f3, the Belen solution just being a try refuted by your retro analysis.
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(7) Posted by Rewan Demontay (Real Name: James Malcom) [Wednesday, Sep 23, 2020 23:36]

I just realized that I had entered in the wrong position, which I've now fixed. Sorry Andrew! In fact, it's actually an Anti-Belen.
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(8) Posted by Andrew Buchanan [Thursday, Sep 24, 2020 02:58]

Why sorry James? The version I posted in response has clean solution & clean retro castling try. It might not have existed if you hadn't posted the wrong diagram at first! There's some other points. Black's last move can only have been R: 1. Kc1xBc2 Bb1xR/Nc2. This is the underlying Belen position, with wKc1 and sound #5. However I preferred to begin in the diagram shown because of this camouflage, and also becomes Meridith Rex Solus with more retro, better keys and the try branches immediately rather than at move 2.

In your new version if I am not wrong there is a single real solution amongst all the dualized castling tries. Whether it is more or less meritorious to have a gaggle of retro try lines or a single one is a matter of taste, I suppose.

I don't know the term Anti-Belen?
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(9) Posted by Rewan Demontay (Real Name: James Malcom) [Thursday, Sep 24, 2020 05:21]

Well I said "sorry" in the event that I wronged you somehow.-you never know after all!

While your version does indeed have cleaner and clearer retro content, the actual solution is dualized. Some retro tries for mine are dualized, yes, but the true solution is unique, which I much prefer. As you said, it is indeed a matter of taste.

As for what an "Anti-Belen" is, see here:
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(10) Posted by Andrew Buchanan [Thursday, Sep 24, 2020 12:06]

Hi James, I was wondering how you might think that my version has duals, when it doesn't. Here are the full solutions:

1. f3! Kxd3 2. Kf2 Kc2 3. Se3+ ~ 4. Rd1#
2. ... Kd2 3. Se3 Kd3 4. Rd1#

1. c4? Kxd3 2. Sc3 Kc2 3. c5 Kd3 4. 0-0-0#?
2. ... Kd4 3. Bd6 Kd3 4. 0-0-0#?

But maybe you have an engine set with "threats" on. But any threats that White has can never be realized, because Black must disrupt them. So it's better imho to set e.g. in Popeye "noth" for problems where Black is very limited in movement.

Is that the explanation?

Having one exact solution remaining out of n possibilities may well be better. Maybe also the aesthetics vary between h# & d#?

The other thread seems to have two different ideas for Anti-Belen: one is Kd3-c1, and the other is Ra1-d1#.
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(11) Posted by Rewan Demontay (Real Name: James Malcom) [Thursday, Sep 24, 2020 15:28]

Oh, silly me Andrew! You are right that your's is dualless-I was thinking that it was Black to move as in mine. You're retro is clean and both clear in the tries and the solution as well. The stipulation could be "#4, & Last 2 Moves?" to complete the Belen theme.

And the Anti-Belen speaks of two ideas because, well, they are both Anti-Belen effects, as equally as valid as the other.

Also, here is the solution to mine:

1. c4? Kxc2 2. Nc3 Kd3 0-0-0#?! But castling is illegal!

1. Nd2+? Kxc2 2. Rd1, Nc4 Kxd3 3. Nc4+, Rd1+ Kc2 4. Ne3# But illegal, as Black as no last move!

1... Ksc2 2. Nd2 Kxd3 3. Nc4 Kc2 4. Ne3+ Kd3 5. Rd1# The actual solution!

I think that the opposite matings by both the knight in the try and the rook in the solution is quite nice as well.
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(12) Posted by Andrew Buchanan [Thursday, Sep 24, 2020 16:19]

Hurray all is resolved!

As far as I can see, I can't quite retract the penultimate last move uniquely: R: 1. Kc1xBc2 Bb1xRc2,Bb1xNc2+. Unless my co-composer (co-mposer?) has spotted something that eluded me? I prefer to keep the stipulation as it is, so that the successful retraction is an Easter Egg for the solver to discover.

I didn't mention the BTM "bluff" exactly because it's twice dualized:

0. ... Kxd3 1. f3! Kc2 2. Kf2 ~ 3. Se3 ~ 4. Rd1#
2. Se3+ Kd3 3. Kf2 Kd2 4. Rd1#
3. Sd5 Kc2 4. Sb4#

But it still serves as a good distraction! :-)

OK two kinds of Anti-Belen exist. I think themes can be exhibited in any phase (e.g. (retro) try), so this is still Belen.
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(13) Posted by Rewan Demontay (Real Name: James Malcom) [Thursday, Sep 24, 2020 20:57]

It certainly is a good distraction! Maybe the stipulation should be "#4 & Last Move?" then to "complete" the Belen "officially" in the solution.
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(14) Posted by Andrew Buchanan [Friday, Sep 25, 2020 02:08]

Actually determining the last move if you are told it’s there is pretty trivial. The interesting trap is that someone might assume that Black can have no last move. I don’t want to change the stipulation to remove that. Any Belen business can all be explained in the solution.
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MatPlus.Net Forum General A fishy Belen