From: Ludovicus on
As there is a Pigeon-hole Principle, I think a new util principle can
be based
in the practice of Sudoku:
"If n cells must be filled with n elements and n-1 cells are
prohibited to
one of those, then that element must fill the free cell."
Ludovicus
From: Arturo Magidin on
On Jun 21, 9:04 am, Ludovicus <luir...(a)yahoo.com> wrote:
> As there is a Pigeon-hole Principle, I think a new util principle can
> be based
> in the practice of Sudoku:
> "If n cells must be filled with n elements and n-1 cells are
> prohibited to
> one of those, then that element must fill the free cell."
> Ludovicus

"Once the impossible has been eliminated, whatever remains, however
unlikely, must be the truth" seems to have anticipated you by 100+
years...

--
Arturo Magidin
From: Herman Jurjus on
On 6/21/2010 6:41 PM, Arturo Magidin wrote:
> On Jun 21, 9:04 am, Ludovicus<luir...(a)yahoo.com> wrote:
>> As there is a Pigeon-hole Principle, I think a new util principle can
>> be based
>> in the practice of Sudoku:
>> "If n cells must be filled with n elements and n-1 cells are
>> prohibited to
>> one of those, then that element must fill the free cell."
>> Ludovicus
>
> "Once the impossible has been eliminated, whatever remains, however
> unlikely, must be the truth" seems to have anticipated you by 100+
> years...

More like 2200+ years (Chrysippus' dog).

--
Cheers,
Herman Jurjus

From: Virgil on
In article
<b490a8f8-008e-40df-a322-9c7b64a0739f(a)i31g2000yqm.googlegroups.com>,
Arturo Magidin <magidin(a)member.ams.org> wrote:

> On Jun 21, 9:04�am, Ludovicus <luir...(a)yahoo.com> wrote:
> > As there is a Pigeon-hole Principle, I think a new util principle can
> > be based
> > in the practice of Sudoku:
> > "If n cells must be filled with n elements and n-1 cells are
> > prohibited to
> > one of those, then that element must fill the free cell."
> > Ludovicus
>
> "Once the impossible has been eliminated, whatever remains, however
> unlikely, must be the truth" seems to have anticipated you by 100+
> years...
>
> --
> Arturo Magidin

But the quote did not appear in quite such a mathematical context.
From: Rock Brentwood on
On Jun 21, 9:04 am, Ludovicus <luir...(a)yahoo.com> wrote:
> As there is a Pigeon-hole Principle, I think a new util principle can
> be based
> in the practice of Sudoku:
> "If n cells must be filled with n elements and n-1 cells are
> prohibited to0
> one of those, then that element must fill the free cell."
> Ludovicus

Conjecture:
If all the digits are used, but one, and are all correctly filled in,
then filling in the last digit will lead to a correct solution.

A Sudoku grid is a 4-D array that embodies the function
S: (a,b,c,d) in U x V x V x U -> S(a,b,c,d) in U x V
The version of the game normally seen has the sets U, V of sizes 3 and
3, so U x V can be expressed as 9 elements, normally taken as the 9
digits.

In this representation (a,b) mark a row, (c,d) a column on the large
grid; (a,c) the (row,column) in a cell. The criteria are that
S_{ab} = S(a,b,_,_),
S_{cd} = S(_,_,c,d),
S_{ac} = S(a,_,c,_)
each be one-to-one functions between U x V and U x V.

So, if all the digits are used but one, and all are correctly filled
out, then each of the above one-to-one functions S_{ab} for all (a,b)
in UxV, S_{cd} for all (c,d) in VxU, and S_{ac} for all (a,c) in UxV
will be correct in all but one place. The Pigeonhole Principle can
then be used.

This is all off the cuff. You may want to take the time to carefully
verify these claims. So, regard my statement as a conjecture, until
someone writes a formal proof.