playstrategy.org

Weekly Challenge 154: Prime Win

#1

Weekly Challenge 154: Prime Win

Win a game of Chess vs @PS-Greedy-Two-Move (or @PST-Greedy-Tom) whilst fulfilling the prime objectives the best:
- Closest to finishing the game on a ply with a prime number
- Closest to capturing a prime number of pieces
- Closest to ending the game with a prime number of pieces on the board

Add up the differences you are from a prime number in these three criterion and that is your score

Adjudication Criteria:
1. Lowest Score
2. Fewest moves (plies) in your game
3. Earliest Entry

Additional Clarification:
- Takebacks are not permitted

This week's challenge is based on idea that was suggested to us by @LowestPosWinRate. If you want to suggest a challenge please message @statmatt or @jheps and it will be considered!

Closing Date: Monday 30th March 1200 UTC+0

#2

49 Ply (Closest prime number is 47, so difference is 2)
6 Captures (Closest prime number is 5 or 7, so difference is 1)
21 Pieces on board (Closest prime number is 19 or 23, so difference is 2)

Score is 5 (2+1+2)

playstrategy.org/P2OyyTQr

#6

Ah wait, is it total my pieces, or total all pieces? So 22 pieces left, 1 away from prime
score 1, 37 ply

#7

I actually cannot say for sure bc I only proposed closest to a prime number of plies.
that out of the way I think total amount of pieces still on the board and number of own captures.

Another question. is it ok that I participate in this challenge or is it the norm that the idea proposer should hold back to ensure a fair competition?

#8

If anybody fears to attempt this challenge bc of its reference to math, then I wanna give you a simple deciding helper of whether a given number below a 100 is prime.

If the number is not obviously divisible by 2, 3 or 5 then there are only three exceptions below a 100.
Namely 49(a square), 77(a repdigit) and 91(same as 21).

So if the number is
1. even or
2. ends with a 5 or
3. is a square or
4. is a repdigit(except for 11 as a repunit) or
5. its digitsum is a multiple of 3 or
6. is 91
then it is not prime.

What the distribution is about: sometimes primes are close to each other?
distance = 2 there are follwing pairs:
3,5
5,7
11,13
17,19
29,31
41,43
59,61
71,73
so representing it as the number of moves so that you have the next move the next chance:(when you play as white)
2
3
6
9
15
21
30
36

So if you aim for a win on move 15 then you can also win on move 16 without affecting the prime constraint.

distance = 4:
3,7
7,11
13,17
19,23
37,41
43,47
67,71
79,83
97,101
again representing in moves so that you have at the move after your next move another chance:(when you play as white)
2
4
7
10
19
22
34
40
49

So if you aim for a win on move 10 then you can also win on move 12 without affecting the prime constraint.

I hope this helps.

#9

@e-pluszak its total number of pieces on the board at the end of the game. So in your example you have 22 pieces remaining and so a score of 1.

@LowestPosWinRate you may take part in this weekly challenge 🙂

Reconnecting