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Draw - possible new feature

 
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photoval
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PostPosted: Wed Mar 29, 2006 5:22 pm    Post subject: Draw - possible new feature Reply with quote

I have a suggestion for DRAW. It would be nice that instead of giving you the answer as a hint, that it would shade in the box to indicate you should be able to figure out this box next and then fill in the number as a second step.

Another feature that would be nice, is if you know you've made a mistake (because you have a box with 2 of the same numbers in it), that there would be a way for DRAW to cross out the entries that are wrong - so you don't have to erase everything and start over.

Thanks.
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alanr555



Joined: 01 Aug 2005
Posts: 194
Location: Bideford Devon EX39

PostPosted: Wed Mar 29, 2006 6:47 pm    Post subject: Reply with quote

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Whilst we are talking about new features, an old request
was for an option to derive the candidates and to post
them as superscripts in the cells before printing.

In my view this should be an option on the initial screen
(ie before the DRAW display is compiled in PDF) so that
it can be invoked ONLY for the initial settings of the puzzle.

The candidates should be set strictly on the basic Sudoku
rules ie:

a) Set each unresolved cell as 123456789.
b) Remove any digit already resolved in same row.
c) Remove any digit already resolved in same column.
d) Remove any digit already resolved in same region.

This should ALWAYS leave at least two candidates for
each cell (should it not???) in a well-set puzzle.

Personally, I prefer NOT to have the candidates derived
as I use the Mandatory Pairs approach to reduce the
possibilities considerably before deriving candidates
(and sometimes never need candidates at all!). However
many human solvers seem to rely upon candidates for
almost everything and this feature would be useful to them.

Alan Rayner  BS23 2QT
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alanr555



Joined: 01 Aug 2005
Posts: 194
Location: Bideford Devon EX39

PostPosted: Wed Mar 29, 2006 6:55 pm    Post subject: Reply with quote

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Yet another suggestion for improvement.

There is an option on the site for the PDF to be either MEDIUM
or LARGE size - a valuable facility!

The default is MEDIUM.
I always use LARGE - which means changing it every time.

I do not mind changing it (something has to be the default
and someone esle got lucky this time) but I do get annoyed
at having to "move" the screen to access the button.

I am using the 1024x768 browser in IE6.
Would it be possible to 'resite' the button higher on the screen
so that one does not need to use the slider bars to access it?

Occasionally, I forget and print out a 'medium' page - one which
does not have enough room for both Mandatory Pairs marks and
the candidates (bottom left and top left respectively).

Incidentally, a similar request would apply if the suggestion of
a user option to print candidate profiles were to be added. The
default should (of course!) be "No Candidates shewn" and so I
would not use the facility - but others undoubtedly will.

Alan Rayner  BS23 2QT
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alanr555



Joined: 01 Aug 2005
Posts: 194
Location: Bideford Devon EX39

PostPosted: Wed Mar 29, 2006 7:04 pm    Post subject: Re: Draw - possible new feature Reply with quote

Code:

> I have a suggestion for DRAW.  It would be nice that instead
> of giving you the answer as a hint, that it would shade in the
> box to indicate you should be able to figure out this box next.

Would this really be of value?
Several contributors (even djb himself!) have opined directly
or indirectly that the hint given is not necessarily the most
relevant next step.

We need to recognise that the hint is derived from COMPUTER
logic rather than from HUMAN logic. Hence the need for someone
like djb (and other regular contributors to this site) to interpret
the former into something understandable in the second catgory.

It was a great IDEA to include a hint (and it does provide the
human solver with a challenge) but its use must be debatable
and the suggestion to highlight the cell without the digit may
even be counter-productive - leading the human solver to a
cell that often is not the most appropriate for attention next
and leading AWAY from the one that is!

Alan Rayner BS23 2QT

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samgj
Site Admin


Joined: 17 Jul 2005
Posts: 106
Location: Cambridge

PostPosted: Sat Apr 01, 2006 6:20 pm    Post subject: Reply with quote

alanr555 wrote:

Whilst we are talking about new features, an old request
was for an option to derive the candidates and to post
them as superscripts in the cells before printing.


This is still on the list. I was reluctant to implement in the old setup because I knew I would replace it sooner or later. Pencil marks will come along to the new draw thing soon, and then this will be do-able.

Quote:
This should ALWAYS leave at least two candidates for
each cell (should it not???) in a well-set puzzle.


Actually in an easy (and most mediums) there will always be one cell with only one option, or only one possible position in at least one row/col/box for a number.

Quote:
There is an option on the site for the PDF to be either MEDIUM
or LARGE size - a valuable facility! The default is MEDIUM.
I always use LARGE - which means changing it every time.


OK -- hopefully I've sorted this. As long as you allow cookies, the next time you make a choice on this it should be remembered for subsequence visits.

Quote:
Quote:
I have a suggestion for DRAW. It would be nice that instead
of giving you the answer as a hint, that it would shade in the
box to indicate you should be able to figure out this box next.


Would this really be of value?
Several contributors (even djb himself!) have opined directly
or indirectly that the hint given is not necessarily the most
relevant next step.


Several people have asked me for this, so I will get to it eventually.

The hint is always a logical step, and it checks simple steps before difficult ones. The problem is that it's dumb -- it starts at row1, col1 and says "can I fill this number in?". Sometimes it can, but using information that would have obviously led to a human filling in another square first.

Sam
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alanr555



Joined: 01 Aug 2005
Posts: 194
Location: Bideford Devon EX39

PostPosted: Fri Apr 07, 2006 11:47 pm    Post subject: Reply with quote

Code:

>> There is an option on the site for the PDF to be either MEDIUM
>> or LARGE size - a valuable facility!  The default is MEDIUM.
>> I always use LARGE - which means changing it every time.

> OK -- hopefully I've sorted this.  As long as you allow cookies,
> the next time you make a choice on this it should be
> remembered for subsequent visits.

Thanks for this.
It works - and it makes use of the site much less irritating!!

I hope that users of this site really do appreciate the way in
which SamGJ attempts to address user-friendliness issues.

Alan Rayner  BS23 2QT
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alanr555



Joined: 01 Aug 2005
Posts: 194
Location: Bideford Devon EX39

PostPosted: Fri Apr 07, 2006 11:56 pm    Post subject: Reply with quote

Code:

> The hint is always a logical step, and it checks simple steps
> before difficult ones.  The problem is that it's dumb -- it
> starts at row1, col1 and says "can I fill this number in?".
> Sometimes it can, but using information that would have
> obviously led to a human filling in another square first.

This explanation is much appreciated - and confirms my suspicion
that the hints may be of little value to humans wanting to learn
something about solving Sudoku.

After the preliminaries, it all comes down to looking for patterns
(in the plain grid or with pencil marks added) and nothing can
avoid the value of intelligent looking. Recently we have had a
link posted to the concept of "Strong Links" between pairs (using
binary properties) which simplifies many of the advanced techniques
BUT - it does all depend upon intelligent looking. From the
explanation above, it would appear that the hint may often direct
us to look in the "wrong" place (wrong to a human anyway) and
so the hint, whilst admirable as an idea, may be detrimental in
practice to the true progress of the human solver. I, for one, have
never used the facility!

Alan Rayner  BS23 2QT
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samgj
Site Admin


Joined: 17 Jul 2005
Posts: 106
Location: Cambridge

PostPosted: Sat Apr 08, 2006 9:32 am    Post subject: Reply with quote

alanr555 wrote:
This explanation is much appreciated - and confirms my suspicion
that the hints may be of little value to humans wanting to learn
something about solving Sudoku.


Well, lots of people do find it useful, but of course, that doesn't mean you should. I believe the cases where the hint is not as obvious as it might be are actually quite rare, but they will be enriched at the steps that the good people are getting stuck. The vast majority of users are likely getting stuck before you might! For what it's work, I haven't yet seen a hint that I can't work out.

Sam
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