A name for this technique please.....

tarek

I thought when I programmed this technique that it was a form of Forcing chains however it turned out to be something else which I don't know know exactly how to describe it.

I would take a poly-valued cell, each candidate of that poly-valued cell is then picked to see what are the implications of it being the actual occupant of that cell.

I use only simple eliminations to study implications (to make it easier for humans), any advanced technique can be used of course.

If another bi- or poly-valued cell turns out to have exactly the same candidates with each candidate from the original cell then we can safely say that the the 2nd cell must have those same candidates (single or poly).

This is not new of course. I just don't know what is its name. There is no Contradiction involved so it shouldn't fit the GENERAL term of T&E.

I'll post the puzzle from which I discovered that I made a mistake in naming the technique. which came from here........

I will also post this on the Players Index....

Ruud · Site Admin

The technique has several names,

but it is most commonly known as Tabling or Forward Implication Chains.

You are only using the part that aims at discovering "verities" or "veracities".

Your technique may be fundamentally flawed if you do not look at contradictions at all. An implication chain that contains one or more contradictions cannot be used in proving a verity or verasity. It must be taken out as if it did not exist. The verities must be proven from the remaining candidates for that cell, verasities by the remaining candidates within the group.

Because you cannot omit the contradictions, this is (and many others will support this position) a form of T&E.

But it is one of the strongest techniques available Smile

Ruud.
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tarek · Posted: Mon Jan 09, 2006 6:32 pm Post subject:

Thanx Ruud,

I have no problem if this turns out to be T&E, I will call it "Forcing Implications", but I thought -because a thin line does exist between The current advanced techniques and T&E- that the general feeling is that only contradiction elimination would mean T&E.

Another issue, this is a thread from the players forums (Link here) from last year regarding a similar position where a human used the technique using pencil & paper. First, it seems logical & doesn't feel like T&E. In most cases you will not reach the level to spot the contradiction if you spotted the implication (Meaning that you will not spot the contradiction if you stop carrying out the implications).

So I have to say that this one is EXACTLY on that Gray line Very Happy

At the moment The function is just before Nishio in my solver, if the general feeling that it is T&E then I'll move it higher up just before Guessing

Olliminatore · Posted: Fri Feb 10, 2006 8:24 am Post subject:

User-friendly internet only solver at sudokusolver.co.uk

Hello, I need also a name of this technique. It is like a "nacked box pair" which i can exclude all other in the row and col, if I know that be the pair can not the same number.

At the last/first Post from me.
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Carcul · Posted: Fri Feb 10, 2006 9:15 am Post subject:

Hi Tarek.

tarek · Posted: Fri Feb 10, 2006 9:53 pm Post subject:

Hi Carcul,

This thread has been started quite a while ago, & things have moved on since Very Happy

If no method was shown from start to finish then it can be T&E, I do agree.

By the way, I have a monster puzzle in preperation. Will post it in the players Index when ready.

Tarek