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Robert Ferre
Joined: 09 Apr 2006 Posts: 10

Posted: Wed May 03, 2006 2:51 pm Post subject: Help from George and Keith 


George, I would he interested in your notation system.
.
Keith, I don't understand unique rectangles. I see the ones that you pointed out, although the cells have other values, too, and similar values nearby. So, I don't understand the logic that leads to the exclusions that you included with each example. I have learned that Xboxes and Swordfish have direction. Is the same true for unique rectangles? 

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Marty R.
Joined: 12 Feb 2006 Posts: 5119 Location: Rochester, NY, USA

Posted: Wed May 03, 2006 3:50 pm Post subject: 


Keith, I just asked a similar question in the May 2 thread. 

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keith
Joined: 19 Sep 2005 Posts: 3150 Location: near Detroit, Michigan, USA

Posted: Wed May 03, 2006 10:30 pm Post subject: Tutorial to come 


Robert and Marty,
Give me a day or two, I will post an introduction to unique rectangles.
Marty,
I was thinking of you the other day. I drove from Detroit to Ithaca, NY, passing close to Rochester. (And with Al Franken on XM radio, broadcasting that day from Rochester!)
Best wishes,
Keith 

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George Woods
Joined: 28 Mar 2006 Posts: 232 Location: Dorset UK

Posted: Wed May 03, 2006 10:36 pm Post subject: 


I label the boxes alphabetically so Box 1 is a and box 9 is i
i.e.
a b c
d e f
g h i
so if the first move is in box e and is the insetion of a 9 I write it down as e9. If I need to refer explicitly to a cell I write it  example Fa i.e. the first cell in box F
Generallysomething like c9 is adequate, and it is hopefully ovious where to put the 9 and why! Otherwise I use additional symbols e.g. underline means "this is the only number that can go in this cell"  i.e see that all other numbers 1 to 9 can be "seen" from this cell. A bar above I use to show that it is deduced by looking along the row, and two bars the column. I use an exclamation mark to show a deduction based on an implied arrangement (e.g.that number must lie in 2 or 3 cells  allowing a deduction elesewhere). No symbol generally means obvious and at the start of a puzzle is usually"only cell that can hold this number", but near the end of a puzzle is likely to be "the only number that is allowed in this cell". I try to use commas to indicate a change of idea, so e673 means 6 then 7 and 3 are entered into e in that order, but done as a "triple" e6,7 implies the 6 and 7 derived from different threads of argument.
I sometimes write f(67) or f66 impling that I have written 67 into two cells, or e66 that 6 lies in only two of the cells, and I write very small 6 in each to remind me.
Clearly you can expand this nomenclature. What I have found is that when a puzzle "explodes", I can backtrack, and usually the mistake turns out to be only one or two moves ago!
I find the alphabetic description easier to use and is more compact e.g Fe is more compact than r5c8 

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Robert Ferre
Joined: 09 Apr 2006 Posts: 10

Posted: Thu May 04, 2006 2:29 am Post subject: 


That was helpful, George. Thanks. It is based not only on numerical possibilities, it also indicates some of the logic involved. I think I can use a little more work on my logic, and my "seeing." I'm working on it.
Robert 

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George Woods
Joined: 28 Mar 2006 Posts: 232 Location: Dorset UK

Posted: Thu May 04, 2006 1:42 pm Post subject: 


For what it is worth here is an example of my solution to today's puzzle (may4)
a1,e1,h1.i1,b7,e4,col2(28)d5,f7,d7,i7,g7c7a7,a5g6,h6,h9,c2,g3,d8g2,d62,a48,c4b4c5,h52,c2,e89,b3,9,c3,e63,f62,c296,i8,g458,f89,i9,i9534,a69
I have used  and  instead of bars over to indicate look in rowand look in column
The col2(2 is put in because it is a key move i.e. scan col2 for 2and 8 and you will find a "hidden pair" 

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