dailysudoku.com

[ZeroAssoluto]

Hi everyone,

[dongrave]

Using just standard VH moves I think you have to use the X-Wing on 9's in cols 1 and 4, the X-Wing on 3's in cols 4 and 7, a 578 XYZ-Wing with pivot at r6c7, and then a 58-3 XY-Wing with pivot at r4c5. After applying the X-Wing on 3's I also saw a 257 XYZ-Wing with pivot at r2c8 but it doesn't look like that was necessary.

[TomC]

An alternative second step to Gianni's post

<25> W wing in r3c9 and r5c3 gives -2 in r3c3

[Mogulmeister]

Another second step using Gianni’s grid is the <248> ANP in r12c2.

If ANP is true then r4c2 = 5 r5c3 <> 5 r8c3 = 5 and r8c9 < > 5
If ANP is false then r2c2 = 8 r3c3 = 2 r3c9 = 5 and r8c9 < > 5

[Mogulmeister]

Don,

Given the variable nature of the grading algorithm, what grade do you think this one was at ?

[peter urhegyi]

Dongrave found 4 of the 5 steps:
1)x-wing on 9's in cols 1&4
2)x-wing on 3's in cols 4&7
3)xyz-wing 578 with pivot at R6C7 (R4C7!=5)
4)xy-wing 58-3 with pivot at R4C5 (R4C4!=3 and R5C8!=3)
I needed one more step:
5a)xy-wing 28-5 with pivot at R3C3 (R8C9!=5 )
or
5b)xy-wing 25-8 with pivot at R3C9 (R8C3!=8 )

[Mogulmeister]

Thanks Peter.

[TomC]

Another second step using Gianni’s grid is -8 in r4c9 as this is needed to avoid the <57> UR in r26c78

This has certainly been the trickiest VH for a while!

[Mogulmeister]

I don't know for sure, but if that had appeared in The Telegraph it might well have been deemed a diabolical ?

[Mogulmeister]

[dongrave]

Thanks for pointing that out Peter! I must have made an error somewhere along the way! I had a tough time with that one!