### Dr. Sudoku Prescribes #55 – Isodoku

or solve online (using our beta test of Penpa-Edit tools)

**Theme:** Peace!

**Rules:** Standard Isodoku rules, using numbers 1-8.

**Answer String:** Enter the 1st “row” on the left edge, followed by a comma, followed by the 4th “row” on the left edge.

**Time Standards (highlight to view):** Grandmaster = 2:00, Master = 4:00, Expert = 8:00

**Solution:** PDF

My guess was that you would have table-cloth sudoku. Isodoku is interesting, but it has a lot in common with Sudo-Kurve.

Given my comment about how Grandmaster Puzzles came from the 2007 WSC, that is a reasonable guess since Tablecloth Sudoku is also now 6 years old. But having published a lot more sudoku, the issues with Tablecloth Sudoku are that (1) it’s not really a sudoku and I’m more formal with names after being at this for much longer and (2) it doesn’t offer as much long-term variety as the types I’ve been trying to highlight. Tablecloth never made one of my books, which means it is sadly a B-lister in the sudoku world.

>> (1) it’s not really a sudoku

What is your definition? I thought it was that the puzzle requires digits 1-N N times each with every space constrained by uniqueness in 3 (or more) different ways (vertically, horizontally and regionally). I guess Tablecloth may violate the “N times each” requirement. But then, so does this Isodoku…

>> (2) it doesn’t offer as much long-term variety as the types I’ve been trying to highlight.

Huh, that’s interesting (or not, I suppose). I’m looking at Isodoku and seeing a lot of overlap with Sudo-Kurve. Individually there’s a lot of variety, but since you can rearrange an Isodoku into a Kurve, you don’t really get much additional variety with both.

>> Tablecloth never made one of my books

Wasn’t it in Mutant-Sudoku? Or maybe I’m misremembering.

Tablecloth has no regions. It is decidedly just a Latin Square variant. It was in the WSC2 book from St. Martin’s but nowhere else that I know of. Are you confusing it with Tile Sudoku maybe?

Isodoku are mostly isomorphic with Sudo-Kurve in a strict sense so maybe I’m voting twice for this kind of genre? I think the two presentations each have their own best subspace of puzzles and those don’t overlap as much.

And it is kind of funny that bathroom tile and kitchen tablecloths have inspired different puzzles, so if that is the confusion it is understood.

Yes, it’s Tile Sudoku that I’m thinking of.

I don’t know what Tablecloth Sudoku is; I guess I should google it. I love Isodoku, although with the more complex ones, I find it much easier to handle when the three surface directions are shaded in three different colors. (This one, of course, was simple to visualize without the shading.)

They were inspired by the competition tablecloth in Prague. You can find the original ones in the middle of the post here. They are definitely “back catalog”, so I’m impressed when people remember them.

5:33 s

I love this 3D Variation.Can solve it all day.This would be favorite so far of the Sudoku variations you have introduced till now motris.Will give mutant sudoku and sudoku masterpieces book a try after seeing this nice sudoku.

I particularly like the way in which a small pencil mark of a number in a edge or a corner gives a dynamo reaction in a totally different corner.

Difficulty level : 6/10

Fun level : 10/10