Sudoku is the king of logic puzzles in the 21st century and WPC deserved his younger brother - WSC, I think we all agree about that. Yes, many debatable puzzles appeared in past WSC's so I support this discussion to determine what can go in future WSC and what can not. However, I think this is a place to ask equally important question - why the older brother remain deprived of sudoku? Even for all the variants that have been disputed for WSC?

Last year in WPC we had 2 low point math sudokus in a whole championship. At the same time we had a full round of 16 skyscrapers puzzles, plus 2 in hexa round, plus 2 in double round, plus 2 in regional round, plus 1 coded, plus final sky puzzles. I did not check the archives, but so many sudokus did not appear in the history of the WPC, including full round in India!? Why? I mean, having a fight for a title of puzzle champion without solving a bunch of most popular puzzles in the world is not normal situation.

What is the solution?

- Again separate the WSC and WPC (reception become more complicated for the hosts, contestants who wish to pursue a priority WPC need to skip WSC as they want be the fittest in fourth and fifth day of solving, etc.),

- Strongly encourage future WPC hosts to include sudoku just like WSC does not exists,

- Allow sudoku variants in Puzzle GP,

- I don't know what else.

And let's suppose that we have come up with the conclusion and defined what is sudoku. What is the next move? Whether the conclusions of the panel will be just a recommendation for future hosts? If they are required, what if some authors put some variant or invent a new one and someone suspects that should not be there? Will organizers be penalized? Will such puzzles be eliminated from the booklet and competition? If I can help somehow in the further discussion, you may count me in.

## READ ME FIRST: What is a Sudoku Committee

### Re: READ ME FIRST: What is a Sudoku Committee

Hi Nikola, thanks for your thoughts.

As I've said in another post, there are a certain number of puzzle solvers who don't really like Sudoku, and given the existence of a WSC, complain that anything about anything that remotely looks like Sudoku in the WPC is overkill and belongs in the WSC instead. Given that the WSC and WPC happen at the same time I suppose it's very tempting for organisers to simply move all the Sudoku puzzles into the WSC.

I've also suggested the emergence of online Sudoku contests is responsible for an ever shrinking proportion of classics at the WSC, and I think there is something to be said for online Puzzle contests shaping the WPC. Firstly, if you select a mix, you have so much choice that it's very easy to ignore any kind of Sudoku in favour of something else (this isn't entirely universal, the USPC I think is a good counter example here) and this thinking might easily transfer over to the WPC. Secondly, if you want to make a whole round on a theme, as many have done with, e.g. Snake, Tapa, Skyscrapers, then you decidedly don't want to pick Sudoku. Because that would make it a Sudoku round and not a Puzzle round.

I think there is much space for Sudoku at the WPC however - I thought it was striking that we have a large number of puzzles from the Turkey 2013 Sudoku GP round posted in this forum. It was a round that displayed a clear concept, and as a puzzle solving experience offered something new and innovative - even if this was a shock to the system for those who prefer a more conservative sudoku solving experience. I have half an idea to put together something for the 24hpc thinking about this.

I'm not sure the committee can hope to dictate what WSC organisers can and cannot include within their competitions, beyond expressing a set of guidelines that express a consensus amongst the community, so that anything that goes against the spirit of the report is effectively going against the spirit of the community and therefore removes a certain credibility and legitimacy from the competition. If the WPF want to go stronger than this, then ultimately that's their affair - but I am not sure the WPF has really had very much control over any WSC or WPC organising team. Anyhow, the committee are writing a report for them and it will be up to them (well, Prasanna or whoever the director is) to decide what to do with it.

If anyone wants to look further into the WPC, then I'm more than happy for people to explore that theme here as I think there's lots of interesting things to consider. However I won't directly take a lead on this, as there is already a great deal for me to think about already!

As I've said in another post, there are a certain number of puzzle solvers who don't really like Sudoku, and given the existence of a WSC, complain that anything about anything that remotely looks like Sudoku in the WPC is overkill and belongs in the WSC instead. Given that the WSC and WPC happen at the same time I suppose it's very tempting for organisers to simply move all the Sudoku puzzles into the WSC.

I've also suggested the emergence of online Sudoku contests is responsible for an ever shrinking proportion of classics at the WSC, and I think there is something to be said for online Puzzle contests shaping the WPC. Firstly, if you select a mix, you have so much choice that it's very easy to ignore any kind of Sudoku in favour of something else (this isn't entirely universal, the USPC I think is a good counter example here) and this thinking might easily transfer over to the WPC. Secondly, if you want to make a whole round on a theme, as many have done with, e.g. Snake, Tapa, Skyscrapers, then you decidedly don't want to pick Sudoku. Because that would make it a Sudoku round and not a Puzzle round.

I think there is much space for Sudoku at the WPC however - I thought it was striking that we have a large number of puzzles from the Turkey 2013 Sudoku GP round posted in this forum. It was a round that displayed a clear concept, and as a puzzle solving experience offered something new and innovative - even if this was a shock to the system for those who prefer a more conservative sudoku solving experience. I have half an idea to put together something for the 24hpc thinking about this.

I'm not sure the committee can hope to dictate what WSC organisers can and cannot include within their competitions, beyond expressing a set of guidelines that express a consensus amongst the community, so that anything that goes against the spirit of the report is effectively going against the spirit of the community and therefore removes a certain credibility and legitimacy from the competition. If the WPF want to go stronger than this, then ultimately that's their affair - but I am not sure the WPF has really had very much control over any WSC or WPC organising team. Anyhow, the committee are writing a report for them and it will be up to them (well, Prasanna or whoever the director is) to decide what to do with it.

If anyone wants to look further into the WPC, then I'm more than happy for people to explore that theme here as I think there's lots of interesting things to consider. However I won't directly take a lead on this, as there is already a great deal for me to think about already!

### Re: READ ME FIRST: What is a Sudoku Committee

I think it is now a good occasion to enlarge the discussion about sudoku puzzles at WPC, too.

I haven't anything to say about it directly, but I've some thoughts related:

I think both arguments can be valid: "WSC puzzles (Sudoku puzzles) should be removed from WPC, because we don't want too much overlapping between the 2 competitions", or "WSC puzzles (Sudoku puzzles) belong to the category of logical, cultural and language-neutral puzzles, so there is no reason to remove this kind of puzzles from WPC, the fact that there is WSC should not influence the WPC". I think a compromise can exist between these 2 positions.

I have 2 fears about this discussion:

Fred

I haven't anything to say about it directly, but I've some thoughts related:

I think both arguments can be valid: "WSC puzzles (Sudoku puzzles) should be removed from WPC, because we don't want too much overlapping between the 2 competitions", or "WSC puzzles (Sudoku puzzles) belong to the category of logical, cultural and language-neutral puzzles, so there is no reason to remove this kind of puzzles from WPC, the fact that there is WSC should not influence the WPC". I think a compromise can exist between these 2 positions.

I have 2 fears about this discussion:

- We have now many different beginning of discussions and questions here: "What is a sudoku?" "Which sudoku are appropriate in sudoku competition?" "What should be the role of classic sudoku at WSC?", and now "How should we treat sudoku at WPC?". I hope that we can have separate answers to all of these questions, but I think the commitee should concentrate on the first one. My fear is that if you begin to crossover arguments between these questions, it becomes just impossible to give clear answers.
- I hope not to see coming arguments that say "We don't want these kind of puzzles in WPC, so it should belong to WSC", as I've seen in the past. WSC is not the WPC trash, and I hope the discussion about WSC will remain a discussion about sudoku. I feel that the answer of the question "what is a sudoku" is crucial and urgent for WSC, it can help further to have a discussion for WPC too (if the question is "how should we treat sudoku at WPC, it's equally important to know what is sudoku".

I don't agree with that: a sudoku round is a puzzle round, in the same way snake, tapa or skyscrapers rounds are. sudoku competitions are puzzle competitions, wsc is and will always be a puzzle competition. I don't understand the new kind of thinking which oppose puzzles and sudoku (you mentionned the WSC 2017 organizers in this thread, too) and could imply that some sudoku are not puzzles.

Fred

### Re: READ ME FIRST: What is a Sudoku Committee

About sudoku variations as defined by drsudoku:

I understand basically what the argument says, and I understand for example that a thermo-sudoku which has only one 2-cells thermometer feels more like a classic sudoku than a thermo-sudoku whose logic has lot of intrications between thermometers (for example the one appearing in round 2 of sudoku GP 2016: http://gp.worldpuzzle.org/sites/default ... Round2.pdf).

But,

Fred

I'll try to explain why I feel very discomfortable with this argument as part of a definition of a category of puzzles.

I understand basically what the argument says, and I understand for example that a thermo-sudoku which has only one 2-cells thermometer feels more like a classic sudoku than a thermo-sudoku whose logic has lot of intrications between thermometers (for example the one appearing in round 2 of sudoku GP 2016: http://gp.worldpuzzle.org/sites/default ... Round2.pdf).

But,

- I think that it is not possible to draw a limit between the 2 extremes.
- I feel that the people who use this argument created a lot of puzzles that are not sudoku variations for sudoku tournaments, according to this argument (For example the WSC 2017 organizers: This argument is valid for the round "Is it a sudoku?" but in other rounds containing variations, you'll find non-negligeable number of variations which need variation constraints extensively to be solved). If someone can enlighten me about a sudoku competition which contains exclusively puzzles which satisfy this condition, I would be glad.
- I think we just use the basic sudoku rules always, even if we forget it and if the logic implied by other constrainst seems more important. Think about a 2-cells killer cage whose sum is 4. You then have to place a 1 and a 3 in the 2 cells. It is the killer constraint that tells it, right? My answer is NO: with killer rule, you can place for example 1½ and 2½, or, if the basic sudoku rule says place number from 0-8, you can place 0 and 4. So even if your brain is working on the extra constraint, you never let it go outside the fact that you need to place numbers from 1-9 in each row, column and region, which are the basic sudoku rules. I feel that (if the goal of the puzzle is uniquely about placing digits in the grid*) it's not possible to separate puzzles in different categories only because the solving techniques are different. To solve a puzzle (and for each digit you place), all rules have to be satisfied, always.

Fred