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Marty R. · Posted: Sun Mar 08, 2009 5:54 pm Post subject:

A one-stepper.

Earl · Joined: 30 May 2007 Posts: 677 Location: Victoria, KS

Two xy-chains remove the 2's in R3C1 & R3C3, which opens the puzzle.

Earl
of the Chain Gang

daj95376 · Joined: 23 Aug 2008 Posts: 3854

The Naked Triple in [b8] can be viewed as an XY-Wing. The pinchers can be extended into a 6-cell XY-Chain.

keith · Posted: Sun Mar 08, 2009 6:53 pm Post subject:

I like this! After basics:

keith · Posted: Sun Mar 08, 2009 7:43 pm Post subject:

After the loop:

tlanglet · Posted: Mon Mar 09, 2009 6:56 pm Post subject:

keith · Posted: Mon Mar 09, 2009 10:35 pm Post subject:

Ted,

I like it! Now, we just have to define a pseudo-cell. How about: A group of two (or more) cells that behave as a single cell in some (simpler) named pattern.

Examples:

1. Type 3 UR

tlanglet · Posted: Tue Mar 10, 2009 12:29 am Post subject:

Keith, that is exactly what I was thinking. And, I don't think is makes a lot of difference if the pseudo-cells are grouped in the beginning, middle, end, or combinations of all; just say how you did it!

We could start a new, more appropriate thread, and hopefully get others to express themselves on this topic including the basic set of terms to be defined.

Ted

Asellus · Posted: Tue Mar 10, 2009 5:18 am Post subject:

My two cents:

By "pseudocell" you mean something that functions akin to a single bivalue cell. What you are really talking about are two dissimilar candidate digits that have a strong inference.

In the case of the "W-Wing" with the 12 pseudocell, the 2-cell 124 ALS in r17c1 produces the 1=2 strong inference: ALS[(1)r7c1=(2)r1c1]. So, you can see this as a form of W-Wing, or as an ALS chain (of which an XY Chain is the simplest example) of 3 bivalue cells followed by the 2-cell ALS. Of course, you can also see it as a 5-cell XY Chain, which might be the easiest view!

But, why stop there? We could see it as a very short ALS Chain, a 2-cell ALS followed by a 3-cell ALS:
ALS[(2)r3c4=(3)r8c4]-ALS[(3)r8c1=(2)r1c1]r178c1
Or, in other words, your standard two ALS technique with shared exclusive <3> and shared common <2>.

So many ways to see the same thing!

In case of the UR Type 3, we have 12UR(3=4). Note that the inference, or "pseudocell", would exists even if this didn't form a Type 3 pattern. (It might be useful in some other way.)

I solved this puzzle using that 6-cell DP Marty pointed out. It can be seen as a sort of 14 "naked pair" involving a DP-induced "pseudocell", though this one involving a grouped digit:
(4)r1c1 - (4=1)r7c1 - 23/25/35DP[(1)r8c1=(4)r3c13]r358c13 - (4)r1c1; r1c1<>4

Thinking of these strong inference pairings as "pseudocells" may help one spot patterns closely related to familiar wing patterns, which has value. But, you can do the same just thinking them as strong inference pairs.