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A weakness in the draw programme

 
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George Woods



Joined: 28 Mar 2006
Posts: 238
Location: Dorset UK

PostPosted: Mon May 08, 2006 12:49 pm    Post subject: A weakness in the draw programme Reply with quote

Today's Mon 8th puzzle Hard starts with 8 fairly simple moves - Fill up row 5 3 numbers into box 1 a 4 into box3 and 2 into box6

We now find box2 is "attacked" by (35) combos that lead to a "hidden pair 35" into row3

Now an analysis of col5 shows the only place for 2 is at row 4... and so on

Curiously Draw finds the first 8 moves, but fails to spot the 2 in r4c5. Asking for hint, expecting this 2 to be revealed, leads to "Too difficult for me" type comment.

Interestingly the puzzle is graded hard after the first 8 moves, and Easy once the 2 is inserted into r4c5!
So perhaps the coder of Draw could investigate
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Chuck Boyer
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PostPosted: Mon May 08, 2006 4:33 pm    Post subject: May 8 puzzle anomaly Reply with quote

I found it even more bizarre.

'Grade' yields difficulty "too hard" after these initial
move(s) : '3' in row 1, col 2 and/or '7' in row 5, col 2.

It later reverts to 'hard', but the 'hint' function fails.

Strange!

Chuck
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PostPosted: Mon May 08, 2006 4:48 pm    Post subject: Re: May 8 puzzle anomaly Reply with quote

Chuck Boyer wrote:

It later reverts to 'hard', but the 'hint' function fails.


After the puzzle grades as 'easy', per George's comment, then the hint function seems to work.

Strange indeed!

Chuck
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Mon May 08, 2006 11:00 pm    Post subject: Reply with quote

I dont know this program, but there was a strange hint mentioned elsewhere. Alternatives are SimpleSudoku, susser, intosudoku and SudoCue, all free.
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David Bryant



Joined: 29 Jul 2005
Posts: 559
Location: Denver, Colorado

PostPosted: Tue May 09, 2006 11:32 am    Post subject: Wad "Draw" modified for X-Wings? Reply with quote

I'm not sure if others have thought of this yet, or not.

We just recently (May 2) saw the very first DailySudoku classic puzzle that _required_ the use of an X-Wing pattern to reach the solution. Most likely, Samgj had to modify the logic in the "Draw" program so that it would recognize this pattern.

I have quite a bit of experience (over 20 years' worth) with computer programming. New bugs are often introduced into existing code -- unintentionally, of course -- when one attempts to add new functionality to a program that already works.

So my guess is that the "strange" behavior of the "Draw" program is associated, somehow, with the recent appearance of the X-Wing, and that Samgj will get it straightened out as soon as he has the time and the energy to do so. dcb
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PostPosted: Tue May 09, 2006 6:47 pm    Post subject: Reply with quote

Excellent point, David!

I cut my programming teeth about 40 years ago on Algol, btw... :wink:

Cheers,

Chuck
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Clement N.
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PostPosted: Wed May 10, 2006 2:47 pm    Post subject: Puzzle On Mon 8-May-2006 Required a little Concentration Reply with quote

After the initial moves i.e 3 in r1c2; 7 in r5c2; 4 in r2c9(lone number) we see that row r5 can be completed as 1 & 9 remain to complete the row. 9 in r9c5 cannot occupy the empty cell in r5c5, therefore 1 should fit that cell and 9 completes the row in r5c8. Now look at BOX1 the numbers to complete the Box are 1,5,6,7 but, 1&6cannot occupy the two empty cells in r2c2 and r3c3. They are left for 5&7; but, 7 is already in r5c2 in BOX4; therefore 5 goes inr2c2 and 7 in r3c3. From there the puzzle becomes manageable somehow.
The grading was proper it was Hard.

Clement. Very Happy
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George Woods



Joined: 28 Mar 2006
Posts: 238
Location: Dorset UK

PostPosted: Wed May 10, 2006 4:54 pm    Post subject: Reply with quote

just for the hell of it I went to draw, today's program (hard) put in the v obvious 2 asked for grade and it became v Hard!!!
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samgj
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Joined: 17 Jul 2005
Posts: 106
Location: Cambridge

PostPosted: Wed May 10, 2006 8:48 pm    Post subject: Re: Was "Draw" modified for X-Wings? Reply with quote

David Bryant wrote:
So my guess is that the "strange" behavior of the "Draw" program is associated, somehow, with the recent appearance of the X-Wing, and that Samgj will get it straightened out as soon as he has the time and the energy to do so.


Energy isn't too much of an issue, but time is :)

There are two different problems here:

George wrote:
Curiously Draw finds the first 8 moves, but fails to spot the 2 in r4c5. Asking for hint, expecting this 2 to be revealed, leads to "Too difficult for me" type comment.


I've been staring at this for a couple of days, expecting it, as David suggested, to be something to do with recent changes. But no, the old version would have also failed with this puzzle -- it should now be fixed though.

George wrote:
just for the hell of it I went to draw, today's program (hard) put in the v obvious 2 asked for grade and it became v Hard!!!


This second issue is less interesting or important -- this month's puzzles have a slightly different definition of hard and very hard, and the draw/play is not yet in sync with this. Actually this kind of thing is ever likely to happen occasionally, because the grade that a puzzle has in the archive is defined on its setting for the first time. The draw/play function takes this grade initially. But when you interactively ask draw/play to grade the current state of a puzzle, then it will be using its currently coded definition of what is hard and what isn't. Check some puzzles from early 2005 (when the gradings were probably a little dodgy) and you'll might find some significant differences.

Sam
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PostPosted: Thu May 11, 2006 1:31 pm    Post subject: May 8th puzzle Reply with quote

A friend of mine and I, who are both new to this game by the way, have been trying to solve the May 8th puzzle. We found matches to the first 8 hints but at that point we get stuck. The next hit puts a 2 in R4C5. Can anyone explain why a 2 goes there for us newbees?

Also, I would like to make a suggestion for a possible enhancement to the "hint" option. I would like to be able to see, in addition to the hint, the reason for the hint. Maybe just the name of the pattern used to arrive at that conclusion would be sufficient.

Thanks.
Brad
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PostPosted: Thu May 11, 2006 6:28 pm    Post subject: Reply with quote

Nevermind. I (actually, my friend) just found it!
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PeteGrant



Joined: 17 Feb 2006
Posts: 10
Location: Saranac Lake, New York

PostPosted: Sat May 13, 2006 6:06 pm    Post subject: Reply with quote

Anonymous wrote:
I cut my programming teeth about 40 years ago on Algol, btw...

Aarrghh!! You beat me, Chuck! I started only 30 years ago; and on COBOL.

My language of choice these days is Java, and I wrote a solver program but it still needs some work as it couln't even solve May 12th "hard" puzzle. (Actually, it did solve the puzzle but only after enabling bifurcation which I don't consider a "legal" method.) I'm still working with the May 12th puzzle, but at the moment I don't see how I can legally get an 8 in R4C6, which is hinted by the draw program. When (or if) I can figure the logic, I can add that logic to my program.
________
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Last edited by PeteGrant on Thu Feb 03, 2011 10:05 am; edited 1 time in total
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ravel



Joined: 21 Apr 2006
Posts: 536

PostPosted: Sat May 13, 2006 8:25 pm    Post subject: Reply with quote

PeteGrant wrote:
... how I can legally get an 8 in R4C6, which is hinted by the draw program.

There is a hidden pair 46 in column 7: rows 2,3 and box 9 already have 4 and 6, so r34c7 are the only cells where 4 and 6 can go to in this column. Thus they are occupied by the numbers and cannot be 8, so that only r4c6 is left for 8 in row 4.
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PeteGrant



Joined: 17 Feb 2006
Posts: 10
Location: Saranac Lake, New York

PostPosted: Sat May 13, 2006 9:10 pm    Post subject: Reply with quote

ravel wrote:

There is a hidden pair 46 in column 7


Aaahh! Another case of the-more-I-looked-the-less-I-saw .... I've gotta stop doing puzzles late at night when I'm tired. I'm a morning person Smile

Thanks Ravel.
________
medical dispensaries


Last edited by PeteGrant on Thu Feb 03, 2011 10:05 am; edited 1 time in total
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Chuck
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PostPosted: Sun May 14, 2006 10:06 am    Post subject: Reply with quote

PeteGrant wrote:
Anonymous wrote:
I cut my programming teeth about 40 years ago on Algol, btw...

Aarrghh!! You beat me, Chuck! I started only 30 years ago; and on COBOL.


It's been interesting to watch the art / science develop over the years, eh? :smile:

I had to write a program in COBOL once, in a Comp Sci class. Not my cup of tea, to say the least; I don't think I ever turned that particular project in. Laughing Got fluent in Fortran in grad school, but now use C++ when I have a choice.

Best of luck with your solver code!

Cheers,
Chuck
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