dailysudoku.com

+------------+----------------+----------------+
| 6 1 x24 | 9 2458 7 | 2458 45 3 |
| 79 3 79 | 458 2458 45 | 24568 1 68 |
| 5 24 8 | 3 6 1 | 7 49 249 | ...

remove <9> from r3c4 to solve

If r3c4=9, <34> pair in row 2 gives r2c2=8, r3c3=9

Look for a deadly pattern to solve this one

There is a 45-56-46 triple in rows 7 and 9

If r7c6 = <56> then the puzzle is invalid as it would have two solutions

So r7c6 = <8> to ...

Gianni

Both your grids are the same!

In one step from the first grid, r2c2=7 to solve

If r2c2=2, r9c13=2 leads to no <2> in column 7

Remove <4> from r6c7 to solve

+-------------------+--------------+---------------+
| 6 7 2 | 3 5 49 | f49 1 8 |
| 9 34 34 | 1 8 6 | 7 5 2 | ...

Another example of forcing a UR - remove <6> from r1c3 to solve

If r1c3=6, r3c3=1, r2c1=2, r7c1=5

Leads to a <12> UR in r17c78

For something a bit more fancy remove <1> from r5c8 to solve
If r5c8=1, r5c3=3, r3c3=4, r8c3=6

Leads to a <35> UR in r78c17

Thanks Gianni

But doesn't a XY wing solve this in one move? No fancy stuff!

I know draw/play says its not easy after this XY wing but it is!

Gianni,

Can you revert to hiding the solutions?

It is not good to have a link to play the puzzle when the solutions are in plain sight below

Grazie

I thought I saw a <129> XY wing in abc, not so, but still helped me remove <2> from r7c5 or r9c9 to solve

+--------+------------+------------+
| 3 8 6 | 2 19 4 | 5 179 179 |
| 2 ...

r3c1 = <9> to solve
Look at the <78> pairs in boxes 4 and 6

If r3c1 = <78> the puzzle would have two solutions

Daily Sudoku puzzles
The Daily Sudoku puzzles: Discussion, help with the logic, and creative solutions

For a creative solution:

r4c6 = <5> to solve

If r4c6 = <18> you would have ...

Remove <8> from r9c7 to solve

+--------------+----------------+----------------+
| 1 6 2 | 458 58 3 | 7 9 458 |
| 45 7 3 | 4568 9 56 | 1 2 458 |
| 459 ...

<17> W wing in r1c1, r4c2 removes <7> in r3c2 or r6c1, otherwise box 7 no <1>'s
or
<17> W wing in r1c1, r4c2 removes <7> in r3c2 or r6c1, otherwise column 3 no <1> ...

There is a pattern of <78> in rows 4, 5 and 6 which means that r4c9 can't be <78> so must be <5>

Has this pattern got a name?

Remove <5> from r5c7 to solve

+---------------+-----------+----------------+
| 469 7 2 | 5 3 69 | 8 14 16 |
| 3 1689 168 | 4 689 7 | c29 5 26 |
| 5 4689 468 | ...

Remove <2> from r6c4 to solve
A short chain leads to a contradiction

If r6c4=2, r6c6=6, r4c6=5, r4c1=7 then no <7>'s in box 5

There is an XY chain 57-79-69-56 in boxes 8 and 9 to remove <5> from r7c5 to solve

Look out for a XY wing 79-1 in there too! (Doesn't solve it in one though)

Remove <3> from r1c4 or r8c5 to solve

+-------------+-----------------+---------------+
| 4 68 2 | a39 b38 5 | 1 3689 7 |
| 1 7 3 | 6 248 29 | 489 489 5 |
...