The New Sudoku Players' Forum

[yzfwsf]

If there are no fireworks, it means that in row 8, besides r8c3, there are other cells not in the 8th box that contain 123. How can you be sure that r9c4=r8c3?

[eleven]

That's obvious. With 5r6c4, r9c4=23. let x be 2 or 3: xr9c3 => -xr8c456 => xr8c3.

[Mauriès Robert]

Hi all,

Here my resolution is based on the tridagon Tr = {123p357B1, 123p139B2, 123p139B4, 123p267B5}
(-7r5c56)=>5r5c5->123r6c348->8r6c1->Tr->... => -7r6c56 and -7r5c79 => (naked quintuple 12359B6) => -5r6c79 => r5c5=7
(-5r6c4)=>123r6c348->8r6c1->Tr->... => r6c4=5 + 5 candidates placed.

The puzzle is then reduced to the point of being easily solved using the usual techniques, for example with anti-track type chains.



(-2r2c2)=>2r5c2->2r456c8->... => -2r2c8 => -2r5c9
(-2r9c1)=>2r9c4->2r8c3->2r1c9->7r6c9->8r6c1->... => -2r6c1
(-2r9c1,-2r5c2)=>(2r9c4 et 2r2c2)->2r4c5->... => -2r4c1
(-2r456c6)=>2r3c6->2r9c1->3r8c3->3r9c4->3r2c5->3r3c1->3r5c2->2r6c3->1r1c3->... r1c4 empty => -2r3c6 => -2r4c5
(-2r2c5)=>2r1c4->2r8c5->2r9c1->2r2c2->... => -2r2c9

(-2r5c2)=>2r6c3->3r8c3->1r7c2->... => -1r5c2

(-3r7c9)=>3r9c7->2r9c4->2r3c1->2r1c9->7r1c7->6r6c7->6r2c9->... => -3r12c9
(-7r1c7)=>7r1c9->2r3c9->2r9c1->3r8c3->3r9c4->3r1c7->... => -1r1c7
(-3r4c5)=>1r4c5->1r1c3->1r8c4->1r6c1->8r6c9->7r1c9->2r3c9->3r3c1->... => -3r4c1
(-1r7c2)=>1r7c1->8r4c1->8r6c9->7r1c9->2r3c9->2r9c1->... 7c1 empty => r7c2=1
(-3r9c4)=>2r9c4->2r3c1->1r1c3->1r8c4->... => -3r8c4
(-3r9c4)=>2r9c4->2r3c1->2r1c9->7r6c9->8r6c1->1r4c1->3r4c5->... => -3r8c5 => r9c4=3 + 20 placements
(-3r3c1)=>3r2c2->3r5c6->... => -3r3c6 , end.