Taxes in? On the review, Wex 428 was easy on us through basic solving. A very generous slink bypass gave us quick box marking and very moderate line marking, with a naked triple to keep us awake.
Again, a potential Sue de Coq on the line marked grid appears, taunting me for missing it before. I kinda’ hope it doesn’t erase the coloring cluster extension via pattern analysis I was planning on.
SWr9 = 5(1+9)(7+8),
or 5 plus naked pair 78.
If (1+9) is an alternate, so is (7+8). But if it’s missing, the two cells in the remainder of r9 can supply the 1 and 9. But if it’s not missing, we can discard the possiblility of a naked pair 78. Then bv19 has to supply 1 or 9 needed in the chute, and 9r9c5 will never be a clue.
So I scratch out a trial trace of SWnp78. It’s a long and tedious one, with a consolation prize in the middle, the naked triple(nt). Whdx9m, stands for “hidden dublex=>W9m”. My hidden dublex is a form of double line exclusion. See Sysudokie Speak.
The SWnp78 is found guilty to a charge of forcing two 7’s into c6.
Now 428 comes apart, as a direct consequence of that 9r9c5 removal. A grouped forcing chain (or ER wink) creates a remote 798-wing, but there are no victims. However, a parallel 8 forcing chain completes a remote pair pair, a.k.a conjugate pair, removing 7r8c6 and confirming 7r3c6 as N7. I wasn’t even aware that could happen!
Listen up, WECer friends: Such revelations happen when you work advanced techniques at the fundamental, sysudokie level. Don’t bypass these catches by guessing! Well, not after your WEC solution is submitted, anyway. Do you have that grouped forcing chain thing down?
The collapse follows immediately. I’m showing the trace to give you another example of a regular 2-D trace. Unlike the trial trace, all consequences of a cause is explored before the next cause its effect list is explored. Its depth first.
The review continues next Tuesday with Wex 429.