Puzzle decorations

Post Reply
Posts: 133
Joined: Mon 09 Aug, 2010 1:53 pm

Puzzle decorations

Post by Fred76 » Fri 11 Jan, 2019 10:59 pm

Sometimes puzzles are not what they seem to be.
For example in round 6 of WSC 2016, an extra-regions was presented as killer sudoku, a windoku as renban sudoku, a diagonal sudoku as pointing different, etc... that's due to the meeting of variant rules on some points (a 9 cells killer cage is an extra-region, etc...). That's fine.

If you look at the tournament unlucky 13 which happened in 2015 on LMI (it was a kind of april fool's tournament): http://logicmastersindia.com/lmitests/?test=M201504S, you'll see that all puzzle are presented as sudoku variations, but all sudoku were classic sudoku (or at least equivalent to classic sudoku). For example, we have some sudoku with extra-regions and all digits in those extra-regions are given. Or a thermo-sudoku with all digits given on the thermometers. That's fine, too.
If I have to write the definition of classic sudoku, then I would see from the rules of the puzzles of the tournament unlucky 13 that the puzzles are not classic sudoku. But the actual puzzles are classic sudoku, because the variations things are just decorations, and you don't need variant rules to solve the puzzles.
My question is then: How much is it a sacrifice to renounce to useless decorations if we have to write a definition and if the decorations and useless rules are outside the defintion?

The 2 examples above have no such issue because everything is about sudoku (in my opinion), so the twist doesn't create a problem. But imagine someone organize a classic sudoku tournament. As an author, I would not give him the puzzles of tournament unlucky 13 (without removing the variation decorations), because rules are confusing and can't be labeled as classic sudoku rules.

I feel this phenomenon appeared to a lesser extent in WSC 2017 round "Is it a sudoku?" where some rules were really only decorative.
The kind of message I understood is that some people don't want a strict definition of sudoku, just because they want to be free to add useless decorations to their puzzles (in that case, the goal was to make a WPC round with same puzzle types as WSC round). Thus my question above: are we ready to renounce to useless decorations?


Posts: 1744
Joined: Mon 21 Jun, 2010 2:25 pm
Location: London, UK

Re: Puzzle decorations

Post by detuned » Sat 12 Jan, 2019 5:00 pm

I'm not sure I understand the question fully - as I don't think what you are describing is much of an issue. As far as I can tell, you are concerned about people being confused by rules which are redundant to solving the puzzle. But as far as I can tell, it's only on very rare occasions that a puzzle then fails to require the use of those rules. The example you posted is a case in point - as an April Fool's concept it is by design supposed to be a bit silly. Anyhow, insofar as this might be a problem, I think this is more a question about good puzzle design than it is about definitions.

However, to twist your idea around, it might be interesting to think about whether it is possible for a given variation to be presented equivalently as sudoku. This tends to rule out any such decorations which come with the caveat that "all possible decorations" are given - which means the absence of the decoration is equally (if not more so) meaningful to solving the puzzle than the decorations themselves.

As I've stated elsewhere, I have no problem with Renban appearing as Windoku, and Killer as Extra Regions. Quite the contrary, I think it is a very useful way to help guide a classification of additional constraints and decorations you can give to Sudoku.

Post Reply