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MatPlus.Net Forum General Jacobs mechanism?
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(1) Posted by Steven Dowd [Thursday, Feb 12, 2009 18:53]

Jacobs mechanism?

In the Pseudo-Kiss discussion, Juraj mentioned a "well-known" Jacobs mechanism. I assume this was named for Walter Jacobs, composer and editor of Chess Review's problem column (1936).

Does anyone have examples of the Jacobs mechanism? It sounds like something it would be interesting to deconstruct.

(Has an article been published on this, somewhere?)
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(2) Posted by Torsten Linß [Friday, Feb 13, 2009 19:08]; edited by Torsten Linß [09-02-13]

It's a collection of focal points. Forgotten the precise definition though I composed one example ages ago

I remember an article by N. Shankar Ram (??) in feenschach 1984 (??).
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(3) Posted by Georgy Evseev [Friday, Feb 13, 2009 23:21]

There are some examples in FIDE Albums, e.g. AF 74-76 #254, 263

Found them searching for orthodox anticipations to my joint problem - 7th WCCT, 4th place in fairy section ;)
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(4) Posted by shankar ram [Tuesday, Jun 23, 2009 19:15]

Hello Torsten!

Yes, I did write an article about the Jacobs mechanism in feenschach in 1984. Need to check whether that issue is online at Kotesovec's site.

Or else I can send a scanned copy. Is there space here for such stuff?
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(5) Posted by Steven Dowd [Tuesday, Jun 23, 2009 23:52]

I would love a scanned copy. 1984 is not one of the available years at Kotosovec.
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(6) Posted by shankar ram [Sunday, Jun 28, 2009 16:20]

Steven, here you go:

Let me know what you think of it!
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(7) Posted by Steven Dowd [Monday, Jun 29, 2009 10:19]

Thank you!
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(8) Posted by Hauke Reddmann [Monday, Jun 29, 2009 10:21]

@Shankar: I don't know what Steven thinks :-) but I think with the
article being from 25 years ago, in the meantime the Jacobs cycle
7*2 and 4*3 might be shown orthodox, ideally with no promoted
material at all. (Nothing against the #2, I was really miffed when
I found out yet another famous dude had anticipated me :-) In any
case, when I saw your article, the first thing I did was reduce
the number of promoted figures in your examples, but since I never
came to zero, it was just a finger exercise :-)

@everybody: *Do* orthodox promo-free 7*2 or 4*3 cycles exist?

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(9) Posted by shankar ram [Monday, Jun 29, 2009 12:18]; edited by shankar ram [09-06-29]

Hauke, The very nature of the theme preempts an orthodox, promotion piece free setting: 7 black pieces, each guarding 2 out of 7 squares in a cycle; 4 black pieces each guarding 3 out of 4 squares in a cycle. And when each black piece moves, it should lose it's guard of the ALL the 2 or 3 squares.

Or did you mean something else?

It would be a Leonid Jarosch like achievement if somebody pulled it off!
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(10) Posted by Steven Dowd [Monday, Jun 29, 2009 20:15]

The first thing I did was look for the 1937 Jacobs problem mentioned; couldn't find it in any database. If anyone has a listing of Jacobs mechanism problems, they would be nice to see. I suppose the more complicated version is used in fairy chess because of the difficulty of doing it with orthodox force.

I haven't begun to think of the more complicated versions of Jacobs, as Hauke mentions, I did find that a #5 I composed did actually use the simplest form of the mechanism, producing some interesting effects. Rather than think about it mathematically, as Ram so nicely described it, I tend to think of such mechanisms more from a intuitive standpoint. His analysis reminded me of the kind of analysis Siers did in some of his articles, very math oriented, very nice to see described in that form. I could never make that sort of analysis, but it is very clarifying to see it like that.

I suspect it has more uses in orthodox problems that have not been explored, but since my matrix was more a coincidence (I had a simple form and just kept thinking, "Wait! If I add this then another focal point is covered and lost with a certain defense until it worked out) I'm not sure I will be the one to do it.

Anyway, it was nice to learn something.
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(11) Posted by shankar ram [Monday, Jun 29, 2009 21:11]

Thanks for your comments, Steven.

(sniff, sniff) Do I smell a whiff of the "intuitive vs. analytical" or "art vs. science" argument here!
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(12) Posted by Steven Dowd [Monday, Jun 29, 2009 21:39]

No, no argument at all. It is just how I do things, by intuition. But I appreciate it when someone can show how the results of this intuition can be demonstrated mathematically, as Siers would do in his articles. In fact, as technical articles go, it was very easy to understand what the point was and how the mechanism might be used. I am not sure *I* can do it, but the blueprint for additional problems using the mechanism is clearly there. I suspect one of my composition partners, who is a scientist, is probably already drawing up matrices, having seen your article......
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(13) Posted by Hauke Reddmann [Tuesday, Jun 30, 2009 10:26]

@Shankar - yup, it IS hard, but especially the 7*2 looks quite
doable zo me. Even if it takes a new Yarosh. :-)


[Sidenote: With #2 I obviously didn't mean a mate in 2 but number 2
from the article.]
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MatPlus.Net Forum General Jacobs mechanism?