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MatPlus.Net Forum Competitions Chess Problems & Studies Discord Composition Tournament #0
 
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(21) Posted by Joost de Heer [Monday, Jun 21, 2021 09:03]

These are the pieces that can move from the line c2-f5 to h5:

24d3
35c2
aod3
bec2
bed3
bee4
bef5
bie4
bte4
cae4
cgf5
cre4
daf5
dof5
eac2
ead3
eae4
eqf5
gee4
gf5
gfd3
glf5
gne4
grd3
gre4
khf5
lef5
lif5
mgc2
mgd3
mge4
mmd3
nd3
nef5
orf5
paf5
qne4
rhf5
rkf5
rlf5
sqf5
wad3
zee4
 
   
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(22) Posted by Andrew Buchanan [Monday, Jun 21, 2021 10:07]

Thanks for this. This confirms the ones we had + lots of hoppers new to me. I'll see if some can be cleanly suppressed. What's the difference between Equihopper and English Equihopper? They are synonymous in BCPS Glossary.
 
   
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(23) Posted by shankar ram [Monday, Jun 21, 2021 11:14]

>>> What's the difference between Equihopper and English Equihopper? They are synonymous in BCPS Glossary.
From the BCPS Glossary:
Equihopper (EQ, English Equihopper): makes the same number of steps either side of the hurdle, in
any direction, can be blocked on any other intermediate square.

Nonstop Equihopper (NE, French Equihopper): makes the same number of steps either side of the
hurdle, in any direction; cannot be blocked on any other intermediate square.

I think there's a bit of Anglo-French rivalry here. Each side seems to have claimed that "their" version was the "true" Equihopper!
 
   
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(24) Posted by Andrew Buchanan [Monday, Jun 21, 2021 11:53]

Thanks, Shankar,
OK, most of these silly equihoppers etc I can do little about, but there's a couple of fun ideas open, and I will send a new version to Joost, if he might be so good as to test.
EDIT: Joost (thank you, thank you) reports that the new ideas work out. Ignoring boring duplicates, but allowing decompositions because they can behave differently, this gives us 10 good solutions, 8 unprovided histories handled by PPRA (mainly equihoppers and sneaky nerfings of actual solutions), 0 major duals & 2 minor duals. So still in good shape.
 
   
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(25) Posted by Andrew Buchanan [Saturday, Jun 26, 2021 11:12]

OK, here is the final version

A.Buchanan after B.Formanek
grateful thanks to J.de Heer
(= 11+2 )
#1 (-:
PPRA 9 solutions
HC+ Popeye mostly

PPRA = Partial PRA = PRA, except we ignore histories which lead to no forward solution. Another mechanism to avoid these might be some kind of help-retraction but I think there's been enough theoretical innovation here. Yes I know PRA talks about "parts" of 1 solution, but that's too erudite.

Restricted to pieces which have actually appeared in published problems. WinChloe includes many units which are not actually to be found in WinChloe problems, and in the walled but splendid garden of WinChloe, I can't run the solving engine exhaustively across all the putative creatures. But Joost de Heer did run Popeye against all creatures in the Popeye catalogue. Thanks very much for this sterling zoological work. So we have:

* 9 clean solutions: Camel, Eagle, Gazelle, Giraffe Quintessence, Greater Leafhopper, Greater Treehopper, Nightrider, Quintessence, Rookhopper
* 7 uncaptures with zero solutions: Bishop Eagle, Boy Scout, Dabbaba, Lancer, Moarider Lion, Radial Leaper, Equihopper.
* 2 minor duals: Gnurider & Marguerite (i.e. solutions separately provided, so ok by my book), and 0 major duals.

As specified, all functional supersets (e.g. Grasshopper) are ignored unless they led to a minor dual, in which case they are recorded for curiosity. Decompositions count as separate solutions. All creatures are in Popeye except for Giraffe Quintessence, which features in P1390964 (b) Norman Gibbins, FCR pre-1946. Most of the 7 non-solutions are nerfed versions of creatures from clean solutions, but Boy Scout blazes a new trail.

Therefore since 9>7+0, I declare this problem sound under the PPRA convention! You may pop your champagne corks now! (-:
 
   
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(26) Posted by Per Olin [Saturday, Jun 26, 2021 11:59]

Inspired by the accomplishment above, here in the heat of the summer a light problem for solving:

Per Olin
Commendation
Thema Danicum New Year Competion 1999

(= 1+1 )

Add two pieces, on a6 and d6, for longest possible helpstalemate with one solution.

Try: +wpa6, +wpd6 H=3 1.Kc8 d7+ 2.Kb8 d8=S 3.Ka8 Sc6=

Solution: +bGa6, +bGd6 (black grasshoppers) H=4 1.Gd8 Kg6 2.Gh6 Kg7 3.Gf8 Kf6 4.Ke8 Ke6=

When with grasshoppers opening the door to the chess zoo, then the composer must be aware of the risks. There can be a longer solution, but with the stipulation given a longer solution does not spoil the problem. There is then a new solution and the present solution is downgraded to a try. Notable is also that two brilliant solutions of the same length will not cook the problem, but the stipulation might well be adjusted. Further refinements can be that the pieces are similar / different / of same or different color etc. - My favorite fairy piece is a neutral zebra.
 
 
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MatPlus.Net Forum Competitions Chess Problems & Studies Discord Composition Tournament #0