Well, it's a little strange that the organisers include devalued rounds in a championship, particularly given the short time limits. I hope you are right that there should be nothing to worry about.

I'm not planning to - although there is definitely a far more pronounced "Puzzle-ish" feel to the whole championships compared to previous years, so I'm not ruling it out either. Qualitative statements on the subject are welcome too, or indeed any kind of indication that the organisers have tested this :-) It's never fun when you start erasing and you suddenly find the printed ink disappearing too...

Erasing may also be a problem for the case the desks are shared by two people and your deskmate makes too much mistakes or trials :) So my question: in individual solving, do we share our desks or not ?

Would it be possible to have the air-conditioning turned off during the rounds? Some people mentioned that in Goa 2008 the outside temperature was nearly 40°C and the competition hall was cooled down to 15-20°C. Is there any chance to avoid such situation?

Yes, we have tested this with multiple testers and brands of pencils and erasers :-)
We've provided a sample grid in the IB (which will be printed on same material as PB). Maybe you can test out your eraser on Sunday? (Its too late to reprint the PB, but if your eraser is strong enough to erase off the grid, we can provide you with an eraser that works better)

I'm a bit curious what exactly you are asking for. Do you want the hall to be 40°C? I'd like to avoid having to puzzle in a 40°C hall. That would truly be insufferable (to me at least).

Two participants will sit on each desk. I think that has been the standard for a few years.

Lets hope everyone gets good deskmates :-)

India is relatively much hotter (and very humid) than most other countries. Switching off the air-conditioning is not an option. We will keep the temperature control where most people can solve comfortably.
Hence, its probably going to be on the cooler side. I can't give an exact number, but my guess will be ~ 20°C.

Participants are coming from different parts of the globe, with different preferences, so it is not possible to get a temperature suited for everyone. I, myself, being Indian, am very comfortable at 30°C, and anything below 25°C is cold and discomforting for me, so, I pick a seat away from the AC vents and bring sweaters / jackets at the championships every year for my comfort. I would recommend you the same.

Unfortunately, I wasn't at WSC 2008, so, I don't know what it was back then.

Perhaps I haven’t explained myself properly!

On my printer, with my paper, I’m happy. But I’m not printing the competition puzzles using either. I’d like to know how they perform using your printers and your paper.

Erasing printed ink can definitely be a problem for certain types of paper especially when laser printed.

I remember shared desk in Beijing and Sofia, not shared desk in London and Senec. I here suggest that if someone will set a standard, not shared desk in individual competition should be chosen.

We have used the same paper quality for multiple offline championships in India (including our nationals in July-2017), and they have stood the test of solvers without any problems.

That is why I suggested you can try out your instruments on the IB we provide you on Sunday, 15th October, since it uses the same ink and paper as the PB. Do you have any other suggestion?
How did you test it last year?

Aahhh ok, I understand now. In Senec, there were two 'desks' touching each other where two participants sat, hence, each one having their own 'desk', but together in pairs. In Sofia, there was one 'desk' where two participants sat together, one on each end.

We preferred one desk per participant. But unfortunately, this wasn't available and we had to go with one larger desk for two participants.

For prizes, what is the criteria of Best debutant(e)? if i have been WSC only 1 time (year 2013), will i be eligible to get thus prize?

This is eligible only for those participating in their first WSC.

Ok good to know that it’s tried and tested at previous competitions, that’s all you needed to say :)

I didn’t test last year as I didn’t really think about it - but I think it was a small problem on some puzzles, which is why I want to be prepared this year. I guess it adds some reassurance if the organisers are able to say they’ve at least thought about this potential issue!

The book defines "Arithmetic Progression" as
"A sequence of digits are in arithmetic progression if every consecutive pair of digits in the sequence have the same difference. The difference cannot be 0."

According to this definition, 2,4,6,4,6,4,6,8,6,4,2,4,6 would be an Arithmetic Progression.

I'm thinking it's safe to assume that the definition is imprecise and that consecutive pairs of digits need to have the same difference in the same direction for it to be an arithmetic progression, but please let us know if there is a chance of a "trick" here.

may

Yes, the pairs have the same difference in the same direction.

Just a general question. Will the Instruction Booklets handed out at the WSC be the latest possible version or have they already been printed?
If they are already printed, is it possible to print an addendum page to be handed with any corrections or clarifications that have been made here since the printing?

It will be the final version.

We will be publishing an entire list of changes along with the final version of the IB on the website / forum.