Author Topic: 20 questions, and the " knot" .  (Read 1578 times)

X1

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20 questions, and the " knot" .
« on: July 07, 2012, 01:18:46 PM »
   It is very hard to imagine what another knot tyer has in his mind, when he is talking about a particular knot... (  It is also very hard to define what " a knot"  is, in general. ) However, it comes out that it is also very hard to read one s mind when he is thinking of "a knot", by playing the 20 questions game !   :)
  In this game, when the other player asks you to answer to questions about an object you have in your mind, you have to answer using a limited only set of responses. ( Yes, No, Irrelevant, Unknown, Sometimes, Maybe, Probably, Doubtful, Usually, Depends, Rarely, Partly ). You are not supposed to provide a more detailed description. Using those responses to any questions he might pose, the other player has to find what you have in your mind. The same game can be played with the "other player" being just an automatic machine - like  the one at :
http://www.20q.net/
   It turns out that it is VERY difficult to pin point the essential characteristics of what we call as "a knot". It is not an object like most of the usual objects we know - it has some objective and some subjective elements, and it is a inseparable mixture of a concrete material thing AND an abstract structure. It seems that "the knot", although it is something we humans are using in everyday life for thousands of years, it is a not a so well-defined or easily-described thing - in some sense, it is many things together ! That is why it is so difficult for the other player or machine to "read your mind" and figure out the "thing" you have chosen, within the limit of 20 questions.
   I have played the game a number of times - and I had won every time ! Another satisfaction that " a knot" had offered to me...  :)
« Last Edit: July 07, 2012, 06:24:17 PM by X1 »

Dan_Lehman

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Re: 20 questions, and the " knot" .
« Reply #1 on: July 08, 2012, 07:55:05 AM »
Of course, if the Answerer hasn't a clear concept of
*knot*, that can make it hard to get helpful answers.

I got :

I am guessing that it is a question?

... and thought "in some sense, it (still) is!"


 ;)

X1

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Re: 20 questions, and the " knot" .
« Reply #2 on: July 08, 2012, 12:35:25 PM »
if the Answerer hasn't a clear concept of*knot*

   But then, who has ? Derek Smith offered the example of a multi-warp turn around the pole , where, provided a sufficiently large number of warps and/or friction coefficient, the mere weight of even a short tail can bear a however heavy loading on the standing end (1) .This "thing" behaves like a hitch, and it seems difficult - even arbitrary - to deny that it is a hitch. However, can we say that it is " a knot" ? I do not thing so (2)(3). But then, how on earth can we have a subset of a set that that it is not included in the set ?  :)

1. http://igkt.net/sm/index.php?topic=3233.msg23454#msg23454
2. " The fact that - as the " capstan equation" and Derek Smith show-, even the very light load of the weight of a short segment of a chord on the one leg can withstand any very heavy load on the other leg - provided that the rope is warped around a round object a sufficiently large number of "single turns"- does not, in my view, forces us to call a multi-warp system by the generic name of "a hitch". The mere accumulation of friction forces by the repetition of many turns can serve to attach a line on a pole or rope, indeed, it can serve to attach a line on an object, it can play the role of a  hitch -  but, at least according to my view of what is a knot (3), it is not a knot - so it is not a hitch, therefore and we should not call it "a hitch". Why it is not a knot ? Because it can be untied, without any obstacles imposed by the topology, the friction, or the mere bulk of the rope. What is prevented by friction ( by the capstan equation and by Derek Smith  :))  is its motion/rotation, as a whole, around the encircled object - or the motion/rotation of the encircled object around it . The multi-warp system is not entangled within itself in a way that would allow us to call it " a knot" ."
3.  http://igkt.net/sm/index.php?topic=3610.msg23443#msg23443
« Last Edit: July 08, 2012, 12:41:24 PM by X1 »