dailysudoku.com

[daj95376]

Rated XY.

[tlanglet]

Notice the Type 3 UR23 in r14c12 provides a pseudocell (479)r1c12.
Now combine that pseudocell with the (79)r1c4 to form an ALS.
From the ALS use the strong inference (4)r1c12 = (7)r1c124.

(4)r1c12 - (4=3)r2c1 - r2c8 = r1c8,
(7)r1c124 - (7=3)r1c8

Thus, both inferences force r1c8=3 to complete the puzzle.

+++++ Edit of first post provided below.

An attempt to describe this as an AIC might be:
ALS{[(7)r1c124 = (4)r1c12]{[UR23(479)r1c12]r14c12 & (79)r1c4} - (4=3)r2c1 - (3=5)r2c8 - (5=7)r7c8; r1c8<>7

Note that the end of the AIC has been adjusted to reflect the deletion of 7 in r1c8 thereby forcing r1c8=3 as previously described.

Ted

[storm_norm]

Ted,

it works...

[tlanglet]

Thanks Norm!

How would you write it as an AIC?

Ted

[storm_norm]

as you have already said, this UR can be used like a type 3.
this means that the extra candidates in the roof cells are going to be shown to have a ALS relationship with other candidates in the row,col,box that the roof cells reside in.
those candidates are {4,7,9} in this case. the other cell that contains these candidates is r1c4 {7,9}
the strong inference that is useful in this situation is between the 7 and the 4.
if the 7 or the 4 is false then you can see that the {2,3} will be the only candidates to remain in the UR cells. and we know that this can't happen. hence the strong inference on any of the ALS candidates, at least one of the ALS candidates has to be true.
we could also write a strong inference on 4 and 9 for example. but this example needs the 7=4.

ALS:479[(7)r1c124 = (4)r1c12]r1c124

the UR is what makes this ALS possible, its the governing factor for this strong inference. so I would include the ALS inside the UR brackets.

UR23{ALS:479[(7)r1c124 = (4)r1c12]r1c124}

now just add the rest of the chain.

UR23{ALS:479[(7)r1c124 = (4)r1c12]} - (4=3)r2c1 - (3=5)r2c8 - (5=7)r7c8; r1c8<>7

[Marty R.]

UR (18), Fin transport (7), UR (59), X-Wing (7) and M-Wing (79).