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MatPlus.Net Forum General What is a "line pin" and are there undefined pins?
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(81) Posted by Neal Turner [Tuesday, Oct 7, 2014 14:02]

Given that we do have difficulty defining many of our terms, the question becomes: Is it important?
It's pretty obvious that Kevin thinks it is, but for most of us it seems not to be.
This majority are happy to go along with the notion: "I can't define it precisely, but I know it when I see it (mostly)."

This might seem a somewhat frivolous position, but don't we have the same situation in many other fields.

Take the staples of Psychology: mind, consciousness, self, personality, memory, intelligence, creativity....
Debate rages about these concepts' very existence, let alone how to define them!

Ok, Psychology is soft science, but isn't the hardest science, Physics, in the same boat:
"There was a time when we wanted to be told what an electron is. The question was never answered... " - Sir Arthur Stanley Eddington
"I think I can safely say that nobody understands quantum mechanics." - Richard Feynman

It's the same all over the place - fundamentals remain undefined or inadequately defined, but it doesn't stop people doing the business.
Why should it be any different for Problemists?
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(82) Posted by Nikola Predrag [Tuesday, Oct 7, 2014 17:53]

the first question might be: Is it important?
But the second question is really important: Is it possible?
So far I don't believe it's possible and pushing WFCC to create and impose some Frankenstein-definitions by all means is certainly not what I will support.

However, I'm very curious about the essence of chess composition and discussing it. In this topic, anyone curious should freely discuss about the topic.
Some concepts were offered but followed by hardly any discussion. Ignoring someone's efforts is not what I find admirable.
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(83) Posted by shankar ram [Wednesday, Oct 8, 2014 09:53]

Hello Nikola..!

I think this thread has gone beyond it's original subject of line pins.. with references to browsers, psychology and quantum mechanics!
All heady stuff..
Now you say you're "very curious about the essence of chess composition and discussing it".. That's my cue for pitching in..!

One of the first books about composition I read was "Chess Problems: Introduction to an Art".. In it, the last chapter discussed in what ways, chess composition would be "useful".. The author, Michael Lipton, made a case that chess problems were a "minor" art and somebody exposed to them would be better prepared to appreciate the "major" arts - like music, sculpture, paintings, plays, etc.

While I didn't fully understand this argument or agree with it.. I have come to accept that it may well be true..

Other than that.. from a composer's point of view, what constitutes the essence of chess composition? The following quote captures a large part of it:

"What delights may its practitioner expect as his reward?

First is the sheer joy of making things. As the child delights in his mud pie, so the adult enjoys building things, especially things of his own design. I think this delight must be an image of God's delight in making things, a delight shown in the distinctiveness of each leaf and each snowflake.

Second is the pleasure of making things that are useful to other people.Deep within, we want others to use our work and to find it helpful. In this respect the programming system is not essentially different from the child's first clay pencil holder "for Daddy's office."

Third is the fascination of fashioning complex puzzle-like objects of interlocking moving parts and watching them work in subtle cycles, playing out the consequences of principles built in from the beginning. The programmed computer has all the fascination of the pinball machine or the jukebox mechanism, carried to the ultimate.

Fourth is the joy of always learning, which springs from the nonrepeating nature of the task. In one way or another the problem is ever new, and its solver learns something: sometimes practical, sometimes theoretical, and sometimes both.

Finally, there is the delight of working in such a tractable medium. The programmer, like the poet, works only slightly removed from pure thought-stuff. He builds his castles in the air, from air, creating by exertion of the imagination. Few media of creation are so flexible, so easy to polish and rework, so readily capable of realizing grand conceptual structures. (...) Yet the program construct, unlike the poet's words, is real in the sense that it moves and works, producing visible outputs separately from the construct itself. It prints results, draws pictures, produces sounds, moves arms. The magic of myth and legend has come true in our time. One types the correct incantation on a keyboard, and a display screen comes to life, showing things that never were nor could be.

Programming then is fun because it gratifies creative longings built deep within us and delights sensibilities we have in common with all men."
(Frederick P. Brooks, "The Mythical Man-Month", 1972)

The above refers to computer programming.. but almost fully applicable to chess problem composing too, I think..
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(84) Posted by Nikola Predrag [Wednesday, Oct 8, 2014 13:49]; edited by Nikola Predrag [14-10-08]

A beautiful and perfectly clear quotation, many thanks Shankar Ram.
Although, I wouldn't exactly agree with "...unlike the poet's words...".
A deep perception of the poetry creates a "vision" of the reality, but with a much deeper perspective than the delusive eyesight allows.

Chess composition is programming the pieces on the board.
And "... Yet the program construct is real in the sense that it moves and works, producing visible outputs separately from the construct itself...."

If the "visible output" (play) is only a medium for the creation of a deeper perspective, the chess composition could be compared with the poetry. At least formally.
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(85) Posted by Kevin Begley [Friday, Oct 10, 2014 21:18]; edited by Kevin Begley [14-10-10]

I have never before encountered a group so eager to make excuses (if not lie) for their own benefit; nor individuals with such an enfeebled vision (even of themselves).
To pretend that elementary problem chess terms are complex -- particularly from those whom have (or would have) accepted titles proclaiming "mastery" in this field -- when the call for honest definitions could be answered by most any child beyond the age of, say, 8 years.

The willingness to pretend that such childish terms must border on the complexity of quantum physics -- hahaha! -- what fools could so masterfully cast these profound webs of self-deceit!!

"Captain of our fairy band,
Helena is here at hand;
And the youth, mistook by me,
Pleading for a lover's fee.
Shall we their fond pageant see?
Lord, what fools these mortals be!"
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(86) Posted by Nikola Predrag [Saturday, Oct 11, 2014 02:21]; edited by Nikola Predrag [14-10-11]

Anyone who ever doubted about master Kevin's understanding of chess composition, now must admit the truth.
Indeed, a deep master's analysis of a "line pin" convincingly proved that we all are just the fools under the age of, say, 8 years.
I'm so happy, now I've have learned not only the secret of fairy chess but also how foolish I was while missing such an honest childish simplicity.
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(87) Posted by Kevin Begley [Saturday, Oct 11, 2014 05:09]; edited by Kevin Begley [14-10-11]


No, in fact, you completely misread my meaning...
It is intellectually dishonest -- not merely childish! -- to pretend that the meaning of elementary chess problem terminology is of a complexity beyond our powers of definition.
One could easily commission a group of elementary school children to define these terms, which have continually eluded this community's greatest depths.
Such a project might prove an quick learning experience for elementary school students, but like an honest conversation about some absurd religion, such a project has the potential to be far too damn revealing (the intellectual fortitude of chess problem enthusiasts might never recover, after suffering the honest appraisal of children).

Face it: these terms are manipulated, for self-interest and favoritism -- their meanings are deliberately left barren, to facilitate a breeding ground for treason against our language.

Bluntly, the problem here is cheating; behind every effort to inhibit the establishment of meaning, for countless elementary terms, you'll find a motivation which reduces to this simplest form of dishonesty.
This community has been cheating, as if there were no price to be paid... as if there were some secondary victim (when, in fact, we only cheat ourselves).

Either provide an ontological basis for the categorization (and jurisdictional divisions) of problem chess, or admit it is based upon deceit -- there is no value in continuing the pretense of an epistemology which precludes any realization of elementary Truth.
I maintain that even babes are capable of realizing an honest foundation, upon which all these terms might derive some legitimate meaning (as each and every term is entitled).

It is the epitome of intellectual dishonesty to advance a known falsehood by asserting (without any shred of evidence) that we might be incapable of realizing honest definitions.
The false claim of quantum complexity is only slightly less laughable than the former claims (which asserted, with no regard for proof, that definitions might be impossible, due to Gödel's incompleteness theorem).
Do not forget, in the midst of such pretense, that the "electron" does have a verifiable definition -- such terms merely advance (very slightly), along with our ever expanding understanding of physics (and our universe).
This is not the issue with basic terms in problem chess -- here, there is a concerted effort to preserve (and benefit from) an intellectually dishonest set of meanings, for every elementary term (which might otherwise provide an honest foundation).
The logic here (denial of any possible definition for: chess, fairy, check, pin, ...) is certainly beyond any Newtonian measurement of a vacuum; but, hey, dishonest observers do not care (nor do those who would silently depend upon them).

This community has allowed itself to occupy a blatantly dishonest position -- it matters nothing that complicity is only discretely conveyed, through a cowardly silence.
Ultimately, we are responsible -- for every fundamental term which we systematically refused to define (including the nature of our affiliations -- especially with our own problem federation).
Childishness is the very least of our troubles.

Furthermore, I do not accept -- nor pursue -- titles which falsely proclaim a "mastery" (I have merely endeavored to discover new ways to express myself, in the form of "chess" problems).
So, I do not acknowledge the false title you attempt to mock me with (though, I suspect you would proudly accept such a title, yourself -- and, ironically, you would do this in spite of your inability to afford it any substantial meaning).
That is all the difference -- I offer this community a pathway to legitimate meaning; you, on the other hand, offer more poor excuses (none of which could withstand the inquiry of a sincere child).
So far, I admit, they overwhelmingly prefer not to hear the truth; but, hey, the clock has not expired. Until then, maybe you could give them a chance -- what do you say?

Georgy, Neal, and Thomas have had no trouble providing us with some insight into a possible meaning for one such term -- and these meanings do advance our understanding.
I have every confidence that any one of them would be capable of providing a complete foundation for all such terms (their meanings are self-evident); and, more to the point, I have every confidence that WFCC is capable of providing a fair arbitration process, to mitigate every semantic dispute.
I say we give them a chance -- give meaning a chance! -- before insisting, a priori, that every problemist must surrender.

This is, after all, not quantum physics; we define problem chess.
It is our choices which determine the meaning of our elementary terms -- we lay our foundation, and upon this, we define our future.

We require one standard -- a universal language which unambiguously describes terminology, spanning every domain of problem chess.
We can not burden the children of the next generation with this duty, nor can we continue to expect that individual software developers will provide this.
This task was appointed to us (and none other), and we dare not refuse it.
We certainly can not afford to presume that every elementary term must have been inherently beyond our capacity to define (or beyond our capacity for semantic compromise/arbitration).
Sorry, but a thousand poor excuses, plus a flag of perpetual surrender, does not constitute an honest try.

In fact, I dare WFCC to officially surrender its own mission -- simply declare that WFCC lacks authority (to arbitrate/sanction rules and guidelines), or better yet, declare that WFCC has found no ability to define a specific set of its own elementary terminology (e.g., WFCC can not distinguish between "Orthodox" and "Fairies").
Either declaration would permit interested parties to collectively organize, toward an honest solution (without any revolutionary disruption).

Just imagine, such a group might resolve its affiliations openly and honestly (by defining itself to serve the interests in ALL DOMAINS OF PROBLEM CHESS) -- it would not be subject to (nor influenced by, nor financially dependent upon) the FIDE (that is: an historically corrupt federation, which purports to represent gamers of a singular -- though evolving! -- rule book).
Imagine not having to suffer a group bent upon advancing the interests of a systematically unfair outcome.
I trust that WFCC will never confess that it lacks governing authority, beyond the FIDE umbrella; and yet, it remains under FIDE -- refusing to define itself.

For those who remotely care about the future of problem chess, there is no value in denying the damage done (so long as elementary terminology is devoid of meaning, the campaign of intellectual dishonesty has proven a complete failure -- notwithstanding the laughable excuses, and pitiable assurances of incapacity).

Nobody is insisting that WFCC surrender all affiliation to FIDE, nor that WFCC forfeit those revenues -- WFCC requires a well-defined reorganization, not a revolution.
WFCC can not continue to idly inflict such damage (the systematic unfairness, the failure to establish universal definitions and standards) upon the integrity of problem chess.

The future of problem chess (and our collective future, therein) depends upon us: our decisions, our definitions, our semantic compromises.
If WFCC does not reorganize to provide us with a legitimate organization, which meets its responsibilities, then revolution will become increasingly unavoidable.
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(88) Posted by Vlaicu Crisan [Saturday, Oct 11, 2014 08:50]

Let's do a summary of the definitions we have so far:

1. Christian Poisson (Problemesis - Glossary)
A piece is pinned if, not being on the board, its King could be captured by a piece which can't do it because it is there.
Pinning is absolute if the pinned piece has no legal move.
Pinning is effective if the pinned piece could move if the pinning piece was not there.

2. Uri Avner (?), completed by Tadashi Wakashima (PCCC - 50):
“Pin” means that the random move or removal of the pinned piece is illegal due to the self exposure of the King to an immediate capture. The pinning may be partial, meaning that the pinned piece is still able to move in a limited way (e.g., along the pin-line).

3. Georgy Evseev:
The piece is considered pinned, if the king of same color becomes checked when we simply remove this piece from board.

4. Thomas Brand:
The effect of a piece {the pinner} that prevents an opposing unit {the pinned unit} due to a subsequent exposed (illegal) check.

All these definitions say the same thing. We have a consistent terminology for the definition of pin.
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(89) Posted by Kevin Begley [Saturday, Oct 11, 2014 10:34]; edited by Kevin Begley [14-10-11]

Actually, Vlaicu, you did not mention Neal's definition (which is quite different); and, even within the set of definitions listed, there were some differences (though, I admit, they hardly show in your summary). Moreover, often these disagreements (listed or not) can be reduced to semantic disagreements.

However, far beyond the differences we might uncover in the definitions provided, it can not be overlooked that all these definitions are excessively orthocentric.
They actually fail, substantially, to uncover the general meaning of PIN, because they all depend upon the orthodox mechanism underlying the PIN (self-check); each of them has failed to consider the general super-form (beyond some mere fairy-forms) of the PIN: generally, the PIN depends upon a revealed ILLEGALITY (self-check is merely a sub-form of illegality).

Generally, a PINNED unit is not prevented from standard possibilities exclusively by the revelation of self-check -- movements may be confined by the more general revelation of a defined ILLEGALITY. For example, consider the Isardam Condition, where it is often said that one may "PIN" a unit, based upon revelation of a defined ILLEGALITY.

I would not too quickly trust that the general term (PIN) can be defined by a collection of such unimaginative, orthodocentric interpretations.
Nor would I be quick to rely upon "anti-" forms (which falsely promise to administer equally to alternative forms of the PIN); particularly, given the fact that "anti-" is a prefix which establishes no clear meaning, with respect to a wide assortment of PIN mechanisms.

I would discourage such a poor methodology (this does not generate logical standards, nor do the semantics establish logical relations).

First, we want to define the "PIN" -- according to the most general definition possible (can you think of a PIN which depends upon the revelation of a term more general than illegality?).
Second, we want to logically subdivide the known alternatives, spanning the broadest possible domain.
Thus, we want to consider the most diverse set of PINs possible -- obtain a better picture of the options before we subdivide a term (With any luck, the full picture will help us to formulate a coherent strategy for semantically dividing the full set).

Only after care is taken to identify the members of the set (and any potential future additions) would I seek semantic suggestions; and, only then would I consider asking WFCC to arbitrate, in the interests of a universal, logical standard.

Please note: I am not arguing for any specific set of petty semantics -- instead, I am arguing for:
1) a coherent, logical naming methodology (which seeks to span the broadest possible domain of problem chess), and
2) WFCC sanctioning authority, which must lie outside the confines (and influences) of its FIDE-Chess umbrella.

Admittedly, self-check is likely to be the most common form of PIN (for some time); thus, no credible attempt to subdivide PINs (e.g., according self-check) goes anywhere, until we first collectively tackle the meaning of check.
What we do know is this: you can not label terms (e.g., "PINs by self-check") according to a predetermined orthocentric name (e.g., PINs), and later attempt to create an unrelated name (e.g., anti-PIN), intending to logically describe the alternatives.
Start with the most general (super-) form of the idea, then logically subdivide each subset (this logical methodology will guarantee that a coherent standard is produced).
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(90) Posted by Nikola Predrag [Saturday, Oct 11, 2014 11:02]

Kevin, open your "room" and host the discussion about what you are persistently talking.
You break in the other "rooms" and impose your, always the same subject.
What are you afraid of? Perhaps that your room wouldn't be much visited?
Speaking of honesty, waiting in your own "room" for visitors would be an honest way to see how interesting is your subject to the others.
But you choose the violence to force the others to listen always the same words. At least say something new, if not about the topic of this "room".

Vlaicu, in the meantime Kevin has answered you, at last about the topic. And he said why the definitions you've mentioned are not good enough, in principle.
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(91) Posted by Kevin Begley [Saturday, Oct 11, 2014 12:59]; edited by Kevin Begley [14-10-11]

Sorry Nikola, this is not your thread -- it happens to be a community thread.
As for your desperate attempt to usher out voices, consider your request "officially denied."
Tell you what: just pretend that censorship is impossible.

First, you claimed that it was impossible to define this term (PIN -- or any other elementary term, for that matter).
You called for complete surrender, because the meaning approaches a complexity beyond your greatest depths (recall that the term, PIN, left you lost somewhere in the electron cloud).

Suddenly, you want to ignore that several others have made an honest attempt to define this very term.
I give all of these people credit -- they all achieved something you considered impossible, and most performed this "miracle" on their first try.
They each made a good individual effort (I'd say most came darn close), but this does not necessarily constitute the final product of a collective agreement.
Sorry kids, but worthwhile compromise is rarely achieved by such abrupt, reactionary amplifications.

There is a more general form... and some further discussion is required.

Listen, Nikola...
Vlaicu certainly does not require you to translate my words (regardless what you may think of your communication skills, that is simply rude, and deliberately obnoxious).

When you were asked for a definition of this term (and others), you only lost ground by staking your white flag in the ground (surrender you said, elementary definitions are impossible).
Now, several honest efforts have made to define this term, and that clearly suggests that surrender (of meaning) is not a valid option.
People generally agree that we are responsible to establish a universal meaning for each of our fundamental terms (nobody is convinced that we should forgo the establishment of some elementary definitions).
Now, where have you left to go, while your false claim is flapping in the wind?

If you claim that it is impossible for you to contribute anything meaningful to these terms... I mean, you do see where this goes, right? Nobody is "forcing you" ("violently") to stay here, and help. You are free to go...

When all of your poor excuses are expired, what argument do you have left?
Hey, I welcome you to remain in this discussion; but, let's not lose sight of our purpose here.
This is a forum for public discussion -- not an outlet to troll for personal attacks.

My interests here are strictly limited to the future of problem chess (and its terminology).
If you have nothing left to offer, in that regard specifically, know this: you will not spoil the opportunity of others, who wish to contribute legitimate ideas.

I understand that you may find it difficult to continue your line of reasoning -- given that your early surrender went nowhere, fast.
Nevertheless, if your comments continue spilling into a personal territory (if that is the only place you have left to go), just know this: I have no interest in making this a personal issue, with you (you will only drag yourself down).
I would encourage you to find a better tact.

You may find it difficult to admit, but this discussion has moved beyond the presumption that no definition is necessary/possible.
Several of us are actively considering the proper methodology to establish a universal definition.
Your surrender of all meaning is duly noted; but, you can not expect that repeating this will preclude ANYBODY from discussing a proper definition of PINS, and LINE-PINs.
Sinking to less legitimate forms of communication (outside the valid use of this forum) will not help your cause, either.

I do not claim to have all the answers; but, I certainly expect that I will be entitled the opportunity to express myself in this discussion, Nikola.
That means: without being personally confronted by somebody interested only in trolling me (or others).
So, if you can not find anything better to contribute, Nikola, please, do us all a favor, and honor your agreements to this forum.

If nothing else, please, consider your strategy: if you goal is to prevent me from talking, it has only backfired.
In fact, quite the contrary, you are behaving as if you have some interest in keeping me (specifically me!) engaged in this conversation.

Others contribute good points... and, I more or less agree with their efforts (there is merit in a variety of interpretations, offered by Neal, Georgy, Thomas, and Vlaicu).
Sure, I happen to prefer that these definitions by expressed in the most general form, and I happen to agree that terminology should be built from the most elementary, up (toward increasing complexity).
This is hardly a radical proposition -- it certainly does not warrant your undo focus on me (I am just one messenger, striving for a better universal standard).
If you refuse to hear these truths, do not blame me.
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(92) Posted by Nikola Predrag [Saturday, Oct 11, 2014 14:44]

Kevin, you project your behavior on me.

- I don't write about your moral or personality but you write about the moral, dishonesty, foolishness of anyone who doesn't support you.

- You write very little about this topic while I've tried to seriously discuss about the pin and the check. You might find my efforts uninteresting or wrong, but you didn't point at what is wrong or irrelevant in my posts about the topic.
Well, nobody else has found my attempts worth discussing, even the initiator of the thread. So, that's the first sign for me that I'm superfluous here.

- "...If nothing else, please, consider your strategy: if you goal is to prevent me from talking, it has only backfired.
In fact, quite the contrary, you are behaving as if you have some interest in keeping me (specifically me!) engaged in this conversation.
I don't try to prevent you from talking, I encourage you to talk about the topic, but without scattering your and our concentration and energy too wide.
You are free to start the thread with any topic, but this thread is not yours as well as it's not mine. It belongs to the line-pin.
You misuse the freedom and heavily burden this topic with the immense off-topic stuff.
Well, since nobody else is complaining about your violence, I must conclude that I'm the only one who sees your use of freedom as a misuse.
Second sign that it's not the place for me.

- I said that so far I don't believe that a complete general definition of fairy chess (including orthodox) is achievable.
However, battery+pin, antibattery+antipin look pretty simple to define, at least up to some level of generalization.

But now I leave.
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(93) Posted by Ian Shanahan [Sunday, Oct 12, 2014 08:25]; edited by Ian Shanahan [14-10-12]

Assuming CHECK has been well defined, the further breakdown of the class of IMMOBILIZATIONS is based on whether or not royalties are involved. So:

1. PIN (accurately described by various contributors here, and NOT just limited to ortho-chess, as Kevin accuses).

2a. PARALYSIS based on OBSERVATION, the latter of which needs careful definition (e.g. Patrol, Paralysing units, etc.).

2b. SPIKING, which can involve non-royalties (e.g Isardam, certain forms of Sentinels, etc.).
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(94) Posted by seetharaman kalyan [Sunday, Oct 12, 2014 09:36]

So, Kevin what is a good definition of Check and PIN.
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(95) Posted by Hauke Reddmann [Sunday, Oct 12, 2014 12:46]

OK, assume we use the broadest possible definition
a la mode Kevin and define: A piece is (partially) pinned when
it's moves are (partially) illegal.
Note that in ortho this is equivalent to standard, since
we can define "move" purely geometrically, avoiding a
loop, and we can define "illegal" with respect to the king.

Alas, can we define "move" purely geometrically for all the
fairy chess versions making us trouble in the first place?
And "illegal?" I fear: Each generic definition promptly will be
counterexampled by an even obscurer fairy variant, up to
the point where the definition is so generic it's useless.

Kevin, please open up a new thread "What is a move?" :-)
Kevin, please open up a new thread "What is illegal?" :-)

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(96) Posted by Nikola Predrag [Sunday, Oct 12, 2014 13:40]; edited by Nikola Predrag [14-10-12]

Ian, there are two questions depending on a direction from which we approach:

1. If we just try to adjust the orthodox definitions to the ever-growing fairy realm, the question is "are we bound to the orthodox thinking?"
2. If we try to create/construct some orthodox-free concepts, the question is "can we consider such a construction as Chess?"

Which are the mandatory essential characteristics of anything that we might consider as Chess?

For practical reasons, we could take Orthodox chess as the initial referential point which shows the essence of a "General concept of Chess".
But during the speculations, we must allow a possible shift of the referential point beyond the borders of Orthodox chess.

Thus, Orthodox chess would be only one "condition" among many other possible (fairy)conditions, without any "privileges".

We should first decide about the approach:
1. Fairy chess is only an alteration of Orthodox chess
2. Orthodox chess is only one variation of "General Chess"
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(97) Posted by Ian Shanahan [Tuesday, Oct 14, 2014 08:02]; edited by Ian Shanahan [14-10-14]

I think an analogy with the concept of 'number' will prove helpful here. We start with the necessary axioms (i.e. on what is mandatory for something to be characterized as [Ortho]Chess) to define Natural numbers {N}. Appending Zero and negative Natural numbers yield the Integers {Z}. Fractions of integers give us Rational numbers {Q}. But there are irrational numbers such as *pi* which, when united with {Q}, give us the Real numbers {R}. Finally, there are the Complex numbers {C = x + iy}, where x and y are Real and i = sqrt (-1). Note that at this point in the taxonomy, each class subsumes the one before it. {C} also is the union of Algebraic and Transcendental numbers - depending on whether or not the number can be a solution to polynomial equations with rational coefficients - a different taxonomy altogether!

Forgive the maths lesson, but note that the process described above did not take place in an historical vacuum and was not without controversy. We can make {N} analogous to Orthochess **AND** simultaneously appreciate that it is a subset of something far bigger. So with Chess.

On another note, our friend Kevin has a mental blind-spot in that he simply cannot tolerate ambiguity. I, however, see ambiguity as a potentially valuable asset - one which allows us to approach a problem from another perspective. Without ambiguity, so much art would never exist. In my own professional field - music - certain agglomerations of pitches can carry more than one label, depending on the *CONTEXT*. So with chess problems.
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(98) Posted by Georgy Evseev [Tuesday, Oct 14, 2014 11:23]

I have stopped writing to this thread when after two days absence I found about 30 off-topic messages.
Now, it seems, the thread has returned to thematic discussion, so I'll try to continue discussion.

Look at this set of cases. I will not give my own answers for now, so you may form your own opinion.

Case 1.


White: Qh5
Black: Ke2 Qb5
(black king is not under check)

Is black queen pinned?

Case 2.


White: Kh5 Qe5
Black: Ke2 Rb5
(black king is under check)

Is white queen pinned?

Case 3.


White: Rh5 Qe5
Black: Ke2 Rb5
(black king is not under check)

Is white queen pinned?
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(99) Posted by Nikola Predrag [Tuesday, Oct 14, 2014 16:05]

(anti)Pins and (anti)Batteries are only our interpretations of the effects of the rules. Rules simply tell us what is/isn't legal and we detect why it is so. We find that some cases are/aren't legal for the same reason(s).

Pin is traditionally based on the orthodox concept of a 'hypothetical illegal selfchek'.
It seems quite logical to consider the pin as a special type of 'immobility'.
'Spike' is another type of 'immobility'. A 'spiked' piece does not check outside the 'spiking-line'.
'Incarceration' is yet another type of immobility etc..

For a bigger picture we should consider another way of generalization.
An occupied square (or a set of squares) might be emptied by some move.
If that would result with a legal check, we call it battery (of some kind).
If that would result with an illegal selfcheck, we call it pin.

The opposite case is when an empty square might get occupied by some move.
If that would result with a legal check, we call it antibattery.
If that would result with an illegal selfcheck, we call it antipin.

Antibattery/antipin are NOT the kinds of battery/pin, they rely on the opposite effects on some square.
Battery/pin are related to the legal/illegal effect of emptying a particular set of squares.

There's a lot of features which could be related and these relations perhaps could make a well described system.
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(100) Posted by Hauke Reddmann [Tuesday, Oct 14, 2014 16:16]

Fide E3.9 -
The king is said to be 'in check' if it is attacked by one or more of the opponent's pieces, even if such pieces are constrained from moving to the square occupied by the king because they would then leave or place their own king in check.
Explicitly in the newest version, which deals with example 2 once and for all. :-)

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MatPlus.Net Forum General What is a "line pin" and are there undefined pins?