I've uploaded a new PB with these changes.

Hello Christian,
2_PLUS_3=5 is accepted as an answer.

For Mechanical Sudoku: Can any of the fragments overlap with one of the existing givens?
For LMI road: can two shaded cells (or half cells (share a side?
stefano

Hi Stefano,
1. It is not forbidden, but the fragments do not overlap each other.
2. Yes.

Hi, what about -2*-4=8? it would give more points but i guess it could also be forbidden since in that case the "-" sign is not really used as an operator

Hello,
If I am not mistaken, CJK's question doesn't have an answer yet. It would be convenient to know if we have to work only with paper/pencil for the optimization problems or not, in order to be rated with the same criteria.
Thank you very much!

?

puzzle 11: only integer numbers or decimal allowed?

The intermediate result can be fractional, but it is forbidden to construct numbers using a dot or comma.

Another request then to get an answer to this question. Not sure why this question has been ignored three times?

Hello,
It would be convenient to know if we have to use only paper/pencil for optimization problems, in order to be rated on the same criteria...

OK. Back to square one on that one.

Hello,
It would be convenient to know if we have to use only paper/pencil for the optimization problems, in order to be rated on the same criteria...

Edited by Carlos 2022-04-20 11:43 PM

Hello,
I always use only paper and pencil, because I am not a programmer.

I see errors in some answers to 12. Record score. Two white players cannot pass to each other if there is a black player on the line between them. And two black players cannot be connected by a straight line if there is a white player between them.

Hello Riad,
I have to admit that it is a little bit frustrating that this simple question cannot be clearly answered by you, even after being repeated five times. I do not really understand why it is that difficult to just say "yes, programming is allowed" or "no, programming is not allowed".
To be clear: I have no clear opinion about whether it should be allowed or not (I haven't programmed yet and I probably won't have time for it anymore), but I dislike the fact that you ignore one specific question for a whole week while answering every other question just a few hours later. For this contest it may be too late, but please don't do this in future contests again.

Hello%2C%0D%0AFor+the+optimizer+equation%2C+exponent+and+negation+are+allow+or+not%3F+Because+technically+exponent+can+be+write+without+using+additionnal+arithmetic+sign%3A%0D%0A9%3D3%C2%B2+et+9+%3D+3%5E2%3F

Hello Christian,
If I knew the answers to all the questions, of course I would have suggested it. I don't program and participate in all tournaments without resorting to this process. Let's leave this question to the discretion of each puzzler.

A couple of questions: For optimizer puzzles, any optimizer puzzle

1. How do you approach to final solution from your initial guess/solution?
2. How do you become aware of that you have reached to the optimum solution?

Please do not use the exponent operator in 11. From 0 to 9.

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That depends on the specific optimizer, but basically I first try to build a solution, any solution. Then to think about how happy I am with that solution in the context of the quantity to be optimized, whether my solution could be improved by small changes, or whether a redesign from scratch, building the solution a different way, would likely give a much better answer. After a few attempts, usually, one has a sense of whether one has produced something good (possibly close to optimal) or if it feels that there are some guiding principles that aren't understood yet. And of course, often, there are BIG surprises when discovering what other people have managed to do with the same optimizer problem. I don't want to comment too much while the contest is going on, plus I'd risk making a fool of myself if I made hasty pronouncements and it turns out my solutions are really really far from the optimal ones, but after initial skepticism I became quite fond of this year's optimizers. I think they are extremely well designed, in the sense that one can profitably approach them by hand and get a sense of how they work; and, if I dare say so, I don't think computer brute force search would be particularly more helpful on these than careful thinking and formulating intuition.

I hope I am not one of those with errors. I have a solution that works well on paper, and proofread what I input into the submission box, but still am not confident that I encoded my solution correctly. Forming the answer key was the least enjoyable aspect of working on this optimizer, perhaps because I feel really bad at encoding/decoding grid coordinates when letters are used in both directions. (The problem itself was very interesting.)

Edited by auroux 2022-04-21 10:55 PM

I was seeing strange messages earlier like "contest is over" and "click link to participate unofficially", even though there is still 13 hours left.
But when I returned to the answer page after submitting it looked normal, so I think they can be ignored...

The contest end time was set incorrectly, hence the confusing error message. It was sorted few hours back.
If anyone else is seeing message like "contest is over", request to refresh the submission page.