UKPA Yajilin Contest (10 Sep - 13 Sep)

Information and discussion on Puzzle Competitions
Post Reply
Feadoor
Posts: 266
Joined: Thu 17 May, 2018 7:08 am

UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by Feadoor »

This is the discussion thread for the upcoming UKPA Yajilin Contest. UK and international competitors are welcome.

Dates: Friday 10 September 2021 - Monday 13 September 2021
Duration: 2 hours
Puzzles: 26 puzzles, including 8 Standard Yajilin and 18 puzzles across a range of variants
Instruction booklet: posted at https://ukpuzzles.org/contests.php?contestid=64
detuned
Posts: 2142
Joined: Mon 21 Jun, 2010 2:25 pm
Location: London, UK
Contact:

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by detuned »

Are the competition puzzles all 6x6 grids?

If not, you should (a) remove the bit in the instructions saying that the examples are a true reflection of the contest grid dimensions, and probably also (b) explicitly point out that grid dimensions may vary significantly from the examples.

(I added that to the UKSC instructions as a small protest against puzzle instruction booklets frequently including unhelpfully trivial and/or small examples!)
Feadoor
Posts: 266
Joined: Thu 17 May, 2018 7:08 am

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by Feadoor »

Haha, well spotted. I did read over everything to check that I hadn't left in anything that didn't make sense or wasn't true but I missed that one.
detuned
Posts: 2142
Joined: Mon 21 Jun, 2010 2:25 pm
Location: London, UK
Contact:

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by detuned »

Happy to help!

Couple of other minor points on the instructions:

For diagonal yajilin, the arrows end up being off-kilter so they don’t point through the grid corner to corner. Maybe it’s therefore worth adding that diagonal specifically means multiples of 45 degrees?

For transparent tapa, it’d be more explicit to use “If part of the loop…” rather than “otherwise…” (I’d also consider swapping the order you describe them, feels a bit clearer to me that way)

It might also be worth spelling out that blackening/shading a domino means two cells sharing an edge. Ditto tromino, which I have to confess looks like a very strange word to me, but apparently that’s all good on Wikipedia (I’m more familiar with triomino)
david mcneill
Posts: 465
Joined: Mon 21 Jun, 2010 2:02 pm

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by david mcneill »

Sam,

In the rules for Look-Air Yajilin, "the total number of distinct squares" is possibly open to misinterpretation. I briefly wondered if it meant "the number of distinct square sizes" e.g. the intended rule is that two single-celled black squares separated by a 4-cell black square is clued by a 3, my misreading would have it clued by a 2.

In Yajiring-ring, "at a point" might possibly be dropped from the rules, as it implies a singular point of intersection. An alternative might be "Different rectangles may intersect each other, but may not turn at their points of intersection or otherwise overlap."

If you have time, it might be good to include solution codes for the example puzzles, if only to convince solvers that the solution code for Yajiring-ring won't present any difficulties.

Examples all work nicely.
Feadoor
Posts: 266
Joined: Thu 17 May, 2018 7:08 am

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by Feadoor »

david mcneill wrote: Mon 23 Aug, 2021 12:28 pm Sam,

In the rules for Look-Air Yajilin, "the total number of distinct squares" is possibly open to misinterpretation. I briefly wondered if it meant "the number of distinct square sizes" e.g. the intended rule is that two single-celled black squares separated by a 4-cell black square is clued by a 3, my misreading would have it clued by a 2.

In Yajiring-ring, "at a point" might possibly be dropped from the rules, as it implies a singular point of intersection. An alternative might be "Different rectangles may intersect each other, but may not turn at their points of intersection or otherwise overlap."

If you have time, it might be good to include solution codes for the example puzzles, if only to convince solvers that the solution code for Yajiring-ring won't present any difficulties.

Examples all work nicely.
Hi David,

I've implemented your suggested change for the rules of Yajiring-ring. For Look-Air (and, to an extent, Double and Triple), I've thought for a while and can't come up with a wording I like which avoids the issue you've highlighted. For the time being, I've changed to word "distinct" to "different", which I think carries a slightly different meaning that makes it less likely to be misinterpreted, but I'm open to further suggestions if you have them!
pin7guin
Posts: 2
Joined: Sun 07 Nov, 2010 12:19 pm

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by pin7guin »

Hello Sam,

in the instructions of Look-Air Yajilin I do not understand, what the following sentence implies:
"Between two blackened squares of the same size there must not be an unobstructed vertical or horizontal run of white cells."

Maybe you could give me an example, what is allowed and what is forbidden by this rule.

Thank you
Feadoor
Posts: 266
Joined: Thu 17 May, 2018 7:08 am

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by Feadoor »

Hi pin7guin,

Here are some examples of the rule in action which hopefully will clear things up.

This situation is not allowed, as the two squares are the same size (both 1x1) and can directly see each other

Image

This situation is allowed, as although the two squares can see each other they are of different sizes

Image

This situation is also allowed, as the line of sight between the two 1x1 squares is blocked by a clue

Image

This situation is allowed, as the line of sight between the two squares is blocked by a square of a different size

Image

This situation is not allowed - even though the squares are not fully aligned, they are the same size and there is a direct line of sight from part of one to part of the other

Image

This situation is allowed, as the only line of sight between the two squares is blocked by one of a different size

Image

And finally, this situation is not allowed, as although one of the possible lines of sight is blocked, the other remains open

Image
pin7guin
Posts: 2
Joined: Sun 07 Nov, 2010 12:19 pm

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by pin7guin »

Thank you!
Now I understand this rule.
detuned
Posts: 2142
Joined: Mon 21 Jun, 2010 2:25 pm
Location: London, UK
Contact:

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by detuned »

Thanks for the contest Sam! It’s fair to say I didn’t leave myself the best slot to take part so I’m not expecting a stellar result, but I enjoyed the puzzles I managed in time, and also out of time finishing off the frustrating ones I worked on during time without having any score to show for the effort.

Definitely on the trickier side for anyone worried about what was a novel take on a well established style - on my part I can say there are one or two of those variants that I’m pretty sure I’ve missed something fairly crucial and still have me scratching my head.
jupilogy
Posts: 41
Joined: Tue 07 Jul, 2020 2:22 pm
Contact:

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by jupilogy »

I enjoyed the ones I did :) Although I ended up breaking quite a few of them...
Feadoor
Posts: 266
Joined: Thu 17 May, 2018 7:08 am

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by Feadoor »

Congratulations to Freddie Hand, who finished the entire set of 26 puzzles in a blistering 48 minutes to win the contest. The podium is as follows:

1. Freddie Hand - 1200 (0:48:01)
2. Endo Ken - 1200 (1:03:29)
3. Prasanna Seshadri - 1200 (1:23:32)

Well done to you all!

A further five competitors submitted correct answers to all 26 puzzles within the time allowed, and the next-best-placed UK competitors were Neil Zussman in 18th with 975 points and Tom Collyer in 29th with 525 points.

Full results can be found here.

The solution booklet is now available on the contest page.
Feadoor
Posts: 266
Joined: Thu 17 May, 2018 7:08 am

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by Feadoor »

I also want to say thanks to everyone who took part. I know there are a number of solvers who were taken aback by the difficulty. I considered applying a warning to the contest beforehand, but I didn't want to 1) scare off people who might have otherwise enjoyed it or 2) influence how the top solvers approached the puzzles.

I hope you all had fun and found some puzzles you enjoyed :)
detuned
Posts: 2142
Joined: Mon 21 Jun, 2010 2:25 pm
Location: London, UK
Contact:

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by detuned »

Are we absolutely sure Freddie was taking the same test as the rest of us? :lol:
david mcneill
Posts: 465
Joined: Mon 21 Jun, 2010 2:02 pm

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by david mcneill »

I was well out of my depth here. Can't remember solving much logically during the test apart from the first Look-Air puzzle. The second Look-Air puzzle was also enjoyable, but that was afterwards. I was able to solve everything eventually using a combination of pen (for certainties) and pencil (for guessing). Shameful! Not very proud of myself.
puzzlemad
Posts: 970
Joined: Mon 21 Jun, 2010 10:20 pm
Location: Oldham

Re: UKPA Yajilin Contest (10 Sep - 13 Sep)

Post by puzzlemad »

I'm still slowly working my way through them, but the logic on my part seems to have ended and am trying to guess methodically. Well done to everyone that did take part in particular Freddie.
Post Reply