dailysudoku.com

tlanglet · Posted: Fri Feb 19, 2010 3:12 pm Post subject:

I wondered around for a four step solution.

storm_norm · Joined: 18 Oct 2007 Posts: 1741

all of those 25's were just too good to ignore.

if the 6 is false in r4c4 then
almost remote naked pair on {2,5} in cells
r9c4, r4c4, r4c6, r7c6

if the 6 is true.
(6)r4c4 - r6c3 = r6c8 - r7c8 = (6-3)r7c9 = (3-7)r7c4 = (7)r7c1
r7c1 <> 25
r7c1 is 7

---------

then using the almost xy-wing {1,3,9} in r69c5 and r8c6
the useless xy-wing is true if the 5 is false in r9c5.
the pincers {1} can be extended to eliminate the 1 in r6c4
xy-wing in red
(1=3)r6c5 - (3=9)r9c5 - (9=1)r8c6 - (1)r3c6 = (1)r3c4

if the 5 is true... leads too
(5)r9c5 - (5=2)r9c3 - r46c3 = r5c2 - (2=6)r5c4 - (6=1)r3c4
either way, the 1 in r6c4 is toast.

tlanglet · Posted: Sat Feb 20, 2010 5:24 am Post subject:

Marty R. · Posted: Sat Feb 20, 2010 5:10 pm Post subject:

There was a flightless W-Wing on 25 in boxes 17 with grouped strong links on both numbers in column 1. I used a pincer transport on each one plus a further extension of the 5. These and an XY-Wing on 391 did it.

storm_norm · Joined: 18 Oct 2007 Posts: 1741

Ted,
yes, its a finned xy-wing.
the finned cell is the cell that contains the extra candidate.
I have a habbit of calling the finned structures "almost" instead of finned.

you could also call the almost remote naked pair a finned remote naked pair.