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MatPlus.Net Forum General What is a "line pin" and are there undefined pins?
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(1) Posted by Siegfried Hornecker [Monday, Sep 22, 2014 10:59]

What is a "line pin" and are there undefined pins?

I have created this position for debate:

(= 2+4 )

Ubi h8

For those less experienced in fairy chess, an Ubi can make any number of knight moves in a row, but only the last one can be a capture. So the Black king is not in check, but it would be if Pb3 or Bc2 is removed.

Black has the legal moves with Pf7, but can also play Bc2-g6, winning the game.
A famous German composer, mathematician and humorist says this is a line pin. Can for a piece like an Ubi the definition "line" really be used? Am I wrong to assume this is an undefined kind of pin other than real, false, line pin.
Or is Hauke Reddmann correct on this issue?

If so, is there any undefined kind of pin?
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(2) Posted by Hauke Reddmann [Monday, Sep 22, 2014 11:15]; edited by Hauke Reddmann [14-09-22]

Another example for my point: a rose pin. wRose e5, bKing h8,
victims g6 and f7. I'm sure nobody has a problem to declare
e5-f7-h8 and e5-g6-h8 a "rose line". Even if the line isn't
straight. (Modern math has no problems whatsoever with lines
that aren't straight in the Euclidian sense and calling them
"straight lines" in appropriate context.)
A bishop pin line is made out of elementar fers steps, and
Ubi-Ubi pin line is made out of elementar knight steps.
I see no conceptual difference.


EDIT: Even simpler example - Mao and Moa pins.
Methinks it would be much more interesting to collect a
list of non-line fairy pin motifs.
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(3) Posted by shankar ram [Monday, Sep 22, 2014 16:05]

My two bits..
I think the term line pin is suitable when pinned piece can move along the line across all the squares that make up the pin line.
So it has to be a piece similar or identical to the pinning piece.
So, an ubi-ubi on c2, instead of Bishop, would fit this interpretation.
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(4) Posted by Kevin Begley [Monday, Sep 22, 2014 17:13]; edited by Kevin Begley [14-09-22]

I'll make you a deal.

(= 2+2 )


1.Kxg6+ (this constitutes an n-tuple check, according to an ongoing quick composing tourney).

If you can tell me the value of n, in this so-called "n-tuple check", then I will try to answer your line-pin question.
Hint: n does not equal 8, if unique paths are the fundamental criteria for tallying checks.

ps: note that "n-tuple check" is a well defined "aim" in many problem stipulations, which is completely contrary to the bogus terminology of the current quick composing tourney.

For the record, I think such tournaments are important, to establish ambiguities in our terminology, but I consider the intentional misuse of terminology a troubling proposition.
Then again, with a governing body which has systematically failed to provide any arbitration for fundamental terminology (our "judges" can not even define check!), a deliberate poisoning of the well might actually be a smarter form of protest.
Reasoning has achieved nothing substantial -- perhaps a systematic unreasonableness is the logical alternative.
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(5) Posted by Hauke Reddmann [Monday, Sep 22, 2014 19:14]; edited by Hauke Reddmann [14-09-22]

@Kevin: That's a trick question, eh? :-)

"8" is the reasonable answer if we count how many blockers
are needed to parry the check. "Unique path" doesn't make
any sense here because the Ubi can make arbitrarily large
detours. So we could talk about "Unique locally shortest path".
("Globally" is also bad - the Ubi checks from b1 which can't then be
part of the path since 4 moves suffice to reach c3.
In contrast, h8-f7-e5-d3-c1-a2 can't be shortened locally.)

We can now backtrack:
h8-f7-g5-e4-c3 1
h8-f7-d6-e4-c3 2
h8-f7-d6-b5-c3 3
(3 globally shortest paths)
h8-f7-d8-b7-d6 (detour, dismiss=DD)
h8-f7-d8-b7-a5 (not even 6, dismiss=D6)
h8-f7-d8-b7-c5-e4 DD
h8-f7-d8-b7-c5-a4 4
h8-f7-d8-c6-b8 D6
h8-f7-d8-c6-a7 DD
h8-f7-d8-c6-b4-a2 5
h8-f7-d8-c6-b4-d5 6
h8-f7-d8-c6-d4-b5 DD
h8-f7-d8-c6-d4-e2 7
h8-f7-d8-c6-e5 D6
h8-f7-d8-c6-e7-d5 8
...and so on, I don't intend to actually count
all different paths to a2,b1,d1,e2,d5,a4
which take 6 moves ;-)

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(6) Posted by Kevin Begley [Tuesday, Sep 23, 2014 10:47]; edited by Kevin Begley [14-09-23]


>"That's a trick question, eh? :-)"

If you consider the move in my diagram to result in an indeterminate number of checking lines, I wonder what this might say about the viability of the definition for n-tuple check, as was given by the recent quick composing tourney (to which I previously alluded)...

Might you actually be suggesting that our problem friends have not carefully considered this matter?
GASP! Surely, they will soon respond to this scurrilous accusation with the proper whole number. :-)
If the tourney promoters wish it, they can meet you with my abacus in hand. LOL.

BTW: I am prepared to meet any attempt to turn the 8 (in the 8-tuple checks) sideways, with an UBI (which I will define as, "an ubiubi devoid of repeating cycles").

I actually considered entering a problem into their previous double-check tourney, using an anti-King.
For those who do not know, the anti-King is in check when not under hostile attack (therefore, by any reasonable definition, the anti-King could never encounter more than a single check).
My idea was to withdraw the hostile attack from two separate units, simultaneously, then claim that this must constitute a "double check" -- taking advantage of WFCC's complete failure to codify a coherent definition for one the most elementary terms in all of problem chess (check).

At first, I deemed that this might expose a potential misunderstanding, concerning the nature of check (therefore, it might have some merit, beyond the thematic content).
Ultimately, I decided against this course, however, because such a problem would necessarily advance an untenable position (one inconsistent with established -- but not yet codified -- norms; it would undermine the consistency of our terminology, and erode the validity of solving tools).

Check is defined, in my view, as a state (something determinate from a position, and in no way a function of move history), rather than some feature of a previous move (like a capture, an annihilation, a castling move, and similar aims).
And, therefore, this must also hold for double check (and n-tuple check) -- just as it holds for checkmate (and n-tuple checkmate).

I, for one, can not in good conscience participate in a tournament which compels the participant to become a party to their own theft.
But, still I wonder whether this might be a worthy exercise, if conducted under a novel terminology (that is, just label it something other than double-check)...

In my view, it could -- providing that the promoters of such a tournament would fulfill their obligation to provide a clear definition for this new terminology.
If they can not provide an algorithm to tally the number of ubiubi "attacking lines" in my 4-man example, I am afraid they can not sincerely claim to have met this obligation.

As to your "line pin" question, I frankly consider it a similar matter.
I count one check from the ubiubi, and I deem it to reside upon a single line (despite the numerous virtual paths, the ubiubi moves as a quantum particle -- existing at point A, and threatening the unit at point B; with no discernible evidence of its path, it becomes utter folly to assert that it must travel along an analog path).
We have no means, whatsoever, to calculate the velocity of such a unit (the distance in squares, per move, is indeterminate).

I would suggest that the ubiubi always travels a straight line between two points, in a curved space (of some degree beyond our reckoning).
Therefore, any such pin must be considered a "line pin."
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(7) Posted by Hauke Reddmann [Tuesday, Sep 23, 2014 11:45]

An even simpler argument for your position (only 1 check):
Kh1 - Rh3 Rf1 Bf3
How many black men must you take off the board to nullify the check?
Three, so it's a triple check.
How many ubi...exactly. :-)


P.S. I don't intend to open another can of worms, but
fairy chess allows a lot of new checking mechanisms
(orphan chains, to name only one random one), for which
the above simple criterion fails miserably.
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(8) Posted by Neal Turner [Tuesday, Sep 23, 2014 12:08]

I don't see how one can criticise the conventions and terminology of Chess, developed on the basis of the orthodox rules and orthodox pieces, for not being inclusive when it comes to weird things like the Ubi-ubi & Anti-kings.

I too looked at the quick composing tourney and decided it didn't fit with my own specialty, SAT - to me it was no big deal.
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(9) Posted by Siegfried Hornecker [Tuesday, Sep 23, 2014 12:23]

I don't want to criticise, I only want to fill gaps that may exist. Apologies if you misunderstood my intention.

For me it is a "range pin" or something like that.
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(10) Posted by Georgy Evseev [Tuesday, Sep 23, 2014 16:05]

I do not see anything really specific in the declared pin, except the possibility of repinning the piece which moves _not_ along the pin line.

See two following examples with roses:

White: Rose a8; Black: Kg8 Rb6

1... Rb6-f6!?


White: Bc6; Black: Ka8 Rose b7

1... Rose b7-b7!?
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(11) Posted by Kevin Begley [Tuesday, Sep 23, 2014 22:09]; edited by Kevin Begley [14-09-24]


"I don't see how one can criticise the conventions and terminology of Chess, developed on the basis of the orthodox rules and orthodox pieces, for not being inclusive when it comes to weird things like the Ubi-ubi & Anti-kings."

WFCC is not merely an orthodox chess problem federation -- though, I certainly understand how it might seem that way! -- I would encourage you to read their charter (

"The goal of ... [WFCC] ... is the dissemination and encouragement of chess composition throughout the world.

The principal activities of the WFCC are derived from its goal; they include:

* the formulation of rules and guidelines in all domains of chess composition."

If WFCC has governing authority over rules and guidelines, in all domains of problem chess, then certainly they have the sole responsibility to establish an unambiguous terminology for elementary terms, including check (and double check, and n-tuple check); their failure to take the first steps towards producing a fairy codex certainly constitutes an abdication of the responsibility that they have reserved for themselves.

Are you honestly suggesting that Fairy Chess should establish an independent Federation?
Because, if that is what you are advocating, I would encourage you to petition WFCC to relinquish authority over all areas which they have neglected, in order that a more responsive Federation might be empowered to properly perform this duty.

Personally, I do not think there is any need to split this federation...
I have repeatedly suggested, for years in the Mat Plus Forum (and elsewhere), that WFCC should commission a diverse committee (with programmers, fairy experts, retro experts, variant gamers, etc), to begin work on a fairy codex (if only making recommendations).
But, WFCC also has a responsibility to account for its biased title system.

I agree with Siegfried -- in fact I could not have said it better myself -- I want only to fill in the gaps!

Trouble is, none of us can individually establish universal definitions -- we require an intelligent arbitrator, to resolve various disputes.
At present, we do not have one.
If that looks like criticism, well, that is because it is simply honest.

It does us little good to debate the meaning of "line pin," with respect to various fairy units, if we have no means to synthesize a universal, unambiguous definition.
People disagree here about the most fundamental terminology (e.g., what is fairy chess, what is double check, etc etc etc), and the disagreements are never adequately resolved.
The best we can do is continue building the list of failures (which, to you, will constantly appear as hostile criticism of the delegates, who do nothing about even the most fundamental failures).

What good the WFCC Judge title, if no two Fairy Judges can agree on the definition of an elementary term (or the scope of their jurisdiction)?
We can not even write the first page of a fairy chess book, because WFCC provides us no definition for our genre!

I gain nothing by exposing the numerous failures of WFCC delegates -- though I can certainly understand that it may seem otherwise! -- I really have only an interest in helping improve the foundation of problem chess (at the very least, to fill in some gaps).
I'd like to see a more logical, clear, and concise foundation -- especially for newcomers (who seem to be divesting from problem chess)!

I'd also like to encourage basic fairness for everyone (composers in all areas are entitled to expect equal treatment).
Presently, WFCC does not even provide any criteria, nor any definition, for their genre sub-divisions.
WFCC provides no reason for the extra points awarded to orthodox study composers (versus even fairy studies, for example).
This is not fairness -- such manipulation, at best, is indicative of a political popularity contest.

Make no mistake about it, WFCC's inaction is not due to any laziness (in the face of a daunting challenge).
Delegates have systematically refused to take even the first step: they refuse to acknowledge any problem (when confronted by numerous failures).
I submit that the cause of inaction is a fear that any changes might impact their ability to manipulate title outcomes.
That conclusion is certainly critical, but I only make such a charge, because I have exhausted all reasonable alternatives.
If this is not the only way to explain their inaction, kindly explain what other motivation would cause them to continually refuse to provide any definition for their own term, "Fairy Chess" (which appears in their own Codex, which constitutes a division in their own Title Album, and which forms a distinct aspect of their own Judge titles).

Why else would they fail to acknowledge that FIDE's alteration of orthodox rules, which trickled into the WFCC Codex, have already bounced several orthodox studies (their intended solutions are no longer valid, under these new rules of orthodox rules)?
If they truly served the interest of those original authors, they would have considered drafting some restoration plan!
Either "orthodox" must be redefined (as a collection of game rules, each one spanning a specific time period), or it must be conceded that the term has only transitory meaning (that all such problems may be reclassified, tomorrow).
This is a binary decision: either they shield orthodox composers against FIDE rule changes, or they do not.

The delegates should have acknowledged the impact of their decision, and clarified the meaning of their terms, if only to inform other problemists who might be considering the restoration of some original works (now potentially lost to orthodox chess, because the game federation changed the rules)!
But, you can not restore (to orthodox) that which resides in WFCC's permanent limbo.

I respectively submit that the delegates want to shirk their responsibilities -- leave such problems neither orthodox, nor fairy.
Many years after this was first brought to their attention, in this forum, they have not even bothered to consider the matter.
They want not to be governed by their own rulings -- they prefer having no rules, and no guidelines, in order to maximize their freedom to influence outcomes (according to the dictates of mood, bias, and favoritism).

How else could two Grandmasters of Problem Chess Composition fail to agree on the meaning of check?

So, you tell me: how do we convince WFCC delgates to do their duty (to serve the best interest of problem chess, in all its domains, fairly), without appearing overly critical of their persistent failure to meet the most elementary responsibilities of their own charter?
Because, I'd really like to help them do what is in their own best interest (and ours).

WFCC's failure to establish universal standards discourages software development, discourages newcomers, undermines fairness, and makes a mockery of the art of problem chess.
The price of WFCC's inaction is snowballing.
That is in no way intended to be critical of the individuals who claim to have been elected -- my only intent is to encourage beneficial change.
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(12) Posted by Nikola Predrag [Tuesday, Sep 23, 2014 22:44]

I'm indeed curious about a general definition of check, applicable in all fairy cases.
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(13) Posted by Ivan Skoba [Tuesday, Sep 23, 2014 23:31]

An interesting article about Ubi-ubi you can see on Vaclav's pages:
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(14) Posted by seetharaman kalyan [Thursday, Sep 25, 2014 10:25]; edited by seetharaman kalyan [14-09-25]

Some find Anti-king and UbiUbi weird. Some will find SAT weird !
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(15) Posted by Hauke Reddmann [Thursday, Sep 25, 2014 13:14]

Some find all fairy chess weird. Heck, I daresay it's the majority
of OTB chessplayers that finds ALL problem chess weird, maybe minus
classic studies :-)
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(16) Posted by Nikola Predrag [Thursday, Sep 25, 2014 15:17]

I find the OTB chess pretty weird. At least, most of the blitz games played in the chess clubs every day offer only a lot of nonsense. Moving the pieces all over the board until someone makes a crucial mistake. Then it becomes interesting, but the opponent often doesn't notice the opportunity and nonsense continues.

If that's not weird, why the chess composition would look weird?
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(17) Posted by Kevin Begley [Friday, Sep 26, 2014 17:28]

All chess is fairy chess. Deal with it.
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(18) Posted by Kostas Prentos [Friday, Sep 26, 2014 21:47]

It is usually the majority that dictates the rules of what is normal and what is weird. Maybe a small minority among those who play chess have seen a chess problem diagram in their lives and have not skipped it in disgust, thinking that this kind of weird stuff will not help improve their game. I do not believe that any of those players will spend a minute trying to understand a fairy problem, especially those problems with the weird pieces turned upside-down or on the side.

Being a retired chess player, I find OTB chess boring, but I still know our place in the whole of the chess spectrum: We are the weird ones. Maybe the study composers are not so much, but the more we differentiate from the standard rules, the weirder we become. I have learned to enjoy being weird and I do not care anymore to attract chess players to what I do. Let them enjoy what they enjoy, and let us enjoy our weirdness. Everybody wins.
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(19) Posted by Nikola Predrag [Saturday, Sep 27, 2014 03:03]; edited by Nikola Predrag [14-09-27]

Well, I retired from OTB chess more than 25 years ago, because it was becoming more and more boring. I was actually attracted by problems as a teenager but I became really interested when I was 40. And one of the reasons for such a "delay" is the "weird perception of problemists" by the OTB players.
However, while still being just an OTB player I was quite often seen as weird by the rest of the world, outside the chess community.
So, now I'm a weird one even for the weird ones :-)

Hm, does my recent curiosity about the fairies make me triple-weird and what is the record of multiple-weirdness?
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(20) Posted by Neal Turner [Saturday, Sep 27, 2014 10:12]; edited by Neal Turner [14-09-27]

It's all very well saying we don't care about the Chess players and cutting our links with the game, but we need the players to provide new recruits into our ever-decreasing circle of problem enthusiasts.

There are many reasons why Problem chess is losing its appeal, but one that it's easy to point to is that we're not making Chess problems any more!
And I'm not just talking about Fairy chess.

Traditionally the most popular form of chess problem has been the orthodox two-mover but even here we've lost the players.
Oh yes, all the pieces are the right way round and the orthodox rules are still in force and the stipulation is the same - so what's the problem?
The problem is that the 'goals' of the modern two-mover are no longer Chess goals.
The goal in the modern two-mover is to produce 'patterns' with the role of the chess pieces reduced to being subordinate to this end.
Now of course I appreciate that this was a natural and inevitable development, but show one of these positions to your average player the result will be a blank stare and a shrugging of shoulders.

Is there any way we can get back to making Chess problems which will have player appeal?
Maybe there is!
In Bern I picked up the latest publication from Schwalbe, an English translation of Herbert Grasemann's book 'Eines Reverends Einfall, der Geschichte Machte' - 'A Cleric's Idea, which made history'.
This is a thorough exposition of the history, development and theory of the New German logical school of composition - maybe for the first time in English.
Reading this book I was struck by the fact that all the examples were real Chess problems displaying real Chess ideas!

With this translation making the principles of the Logical School more accessible, possibly we could see a resurgence of this type of problem - problems which you can show to your chess-playing friends!
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MatPlus.Net Forum General What is a "line pin" and are there undefined pins?