The New Sudoku Players' Forum

[jovi_al01]

hello all, a few months ago i made a puzzle using a sudoku technique that i would like to share here. forgive me, as i am not yet familiar with notation.
consider this puzzle i made to showcase this technique:

Code: Select all

..3.1...5.8.7.........2.4........1...9.4...8.2.......34.6....5..5.879..........7.

spoilers for intended solution path are below:

Hidden Text: Show

naked single 3 in r7c5.
consider SET (r5 plus c2,8 plus b7) minus (r1,3 minus b4,6)
because {123} as givens appears twice in one partition, they must appear twice in the other (via the SET).
this means that r8c1,3 (whatever they may be) must appear somewhere in the other partition.
they see r8c8 in the row, and r5c5 cannot contain {123}.
r8c1,3 = r2c8, r5c6.
from there it is fairly simple to prove that r2c8, r5c6, r8c1, and r8c3 cannot contain 3.
btte

i think of this as some form of senior exocet. i have been calling it a mutant exocet. i must thank mith for inspiring me to work on this.

[marek stefanik]

Hi jovi_al01,
Very interesting twist on exocets!

My non-SET proof is very similar (just uses r2 instead of b7):

Code: Select all

             12                                                12
   +------------------------+------------------------+------------------------+
   | 679     24      3      | 69      1       468    | 78      269     5      |
   | 1569    8       24     | 7       4569    3456   | 2369   T12369   1269   | 12
   | 15679   16      1579   | 3569    2       3568   | 4       1369    78     |
   +------------------------+------------------------+------------------------+
   | 35678   346     4578   | 23569   5689    23567  | 1       2469    24679  |
   | 13567   9       157    | 4       56     T123567 | 2567    8       267    | 123
   | 2       146     14578  | 1569    5689    1567   | 5679    469     3      |
   +------------------------+------------------------+------------------------+
   | 4       7       6      | 12      3       12     | 89      5       89     |
   |B13      5      B12     | 8       7       9      | 236     12346   1246   |
   | 89      123     89     | 56      456     456    | 23      7       12     |
   +------------------------+------------------------+------------------------+

Br8c13; Tr2c8, Tr5c6; cross-lines 12r25c28, 3r5; cover-houses 1b134, 2b136
-567r5c6, -369r2c8

The puzzle also contains a simpler exocet with the same base (targets r2c8 and r7c4), which finishes the job.

[jovi_al01]

thank you for taking a look at it marek! and i've just realized i made a repeated typo in the original post (in which i typed r7 instead of r8 multiple times)-- how embarrassing!