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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Mon Aug 20, 2007 12:33 am    Post subject: Reply with quote
Thanks MM. I don't agree, but at least I have a better understanding. Does that mean that you have similar feelings about BUG+1, since that is based on uniqueness as well?
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keith



Joined: 19 Sep 2005
Posts: 3355
Location: near Detroit, Michigan, USA
PostPosted: Mon Aug 20, 2007 1:27 am    Post subject: Reply with quote
Quote:
Incidentally, I'd be interested to see if anyone has been able to create a puzzle that could only be solved if a UR was used.

There are plenty of examples where Uniqueness arguments solve very difficult puzzles. Including some previously unsolvable.

The problem with this discussion, as I have previously remarked, is that you have to first decide on a hierarchy of solving techniques. Is a type 1 UR more or less complicated than a finned jellyfish? How many angels fit on the head of a pin?

MM, I am with you in that I don't use solving techniques on puzzles that I know don't "need" them. For example, The Fiendish Sudoku can always be solved by basic methods. This is not to say that finding the hidden quad is easy. But, I ignore the obvious X-wings and UR's, because I know they are not "necessary".

MM, try this:
Code:
2 5  1  |7 4   8|9  6  3
3 9  4  |6 5   2|7  18 18
6 7  8  |1 3   9|4  5  2
--------+-------+--------
5 26 267|9 8   3|12 4  17
1 8  3  |4 2   7|5  9  6
9 4  27 |5 1   6|28 3  78
--------+-------+--------
8 3  69 |2 679 4|16 17 5
4 26 5  |8 67  1|3  27 9
7 1  269|3 69  5|68 28 4

I have not looked at it for over a year. It is from the days before finned fishes and W-wings. How would you solve it?

Keith

By the way, my mother-in-law is an idiot, at least insofar as her left turn rule applies.
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Mogulmeister



Joined: 03 May 2007
Posts: 1151
PostPosted: Mon Aug 20, 2007 1:28 am    Post subject: Reply with quote
Keith,


XY chain with pincers at r4c7 and r7c8 to take out the 1 at r7c7 - I suspect.

You with the <69> UR ?

Marty,

I did say it was my personal view - I'd usually exhaust other techniques before going to UR or indeed BUG.

To be honest though, it may be the way I solve, but I have never really needed BUG whereas I have used UR when in a tight corner on an extreme.
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Marty R.



Joined: 12 Feb 2006
Posts: 5770
Location: Rochester, NY, USA
PostPosted: Mon Aug 20, 2007 4:10 am    Post subject: Reply with quote
Quote:
I did say it was my personal view - I'd usually exhaust other techniques before going to UR or indeed BUG.


MM, I realize you were stating your personal view. I hope you didn't think that I thought you were stating opinion as fact, because that certainly wasn't the case.
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Mogulmeister



Joined: 03 May 2007
Posts: 1151
PostPosted: Mon Aug 20, 2007 1:36 pm    Post subject: Reply with quote
Not at all Marty. Smile
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