Author |
Topic: Haizhi's unconnected-step pruning (my notes) (Read 4680 times) |
|
aaaa
Forum Guru
Arimaa player #958
Posts: 768
|
 |
Re: Haizhi's unconnected-step pruning (my notes)
« Reply #15 on: Feb 26th, 2009, 2:48pm » |
 Quote  Modify
|
on Feb 26th, 2009, 11:03am, Hannoskaj wrote:By the way, I have also played at making a position where the only winning move is making four uncorrelated steps.
Here silver goals in two (ha6 mc1 ec7 cg7), but any other move is a loss in two, if I am not mistaken (typically Db2 to defend (or Cb4 if free) and Db6 Ra6).
Silver: r d8 e7 d6 a5; c h7; d b6; h a7 e5; m d1; e b7
Gold: R d5 d7 g6; C b5; D b1 g4; E e6
|
|
Bot-assisted analysis bears out that you have succeeded in your goal. Minor corrections are that ha7s md1w eb7e ch7w is actually a goal in three (since rd6w Ee6w Rd5w Cb5s delays the goal for one more move) and that there is one other move that is not a loss in two, eb7e ec7n Rd7w ch7w, but this still loses in three.
Quote:| By the way, is there any agreeable way to post a position ? |
|
See http://arimaa.com/arimaa/learn/notation.html, under "Notation for Recording Arimaa Positions".
|
|
 IP Logged |
|
|
|
Janzert
Forum Guru
Arimaa player #247
Gender: 
Posts: 1016
|
|
Re: Haizhi's unconnected-step pruning (my notes)
« Reply #16 on: Feb 27th, 2009, 4:32am » |
Quote Modify
|
Hannoskaj
It seems your first position has a related first and second step.
For your first position to move Re3n:
+-----------------+
8| . . . . . . . . |
7| . . . . . . . . |
6| . . x . . x . . |
5| . . . . . . . . |
4| . . . . C e . . |
3| . . x d R R . . |
2| . . . . . . . . |
1| . . . . R . . . |
+-----------------+
a b c d e f g h
Re1n Re2e Ce4w Re3n
But maybe I'm misunderstanding it as I did the goal example initially.
Janzert
|
| « Last Edit: Feb 27th, 2009, 4:45am by Janzert » |
IP Logged |
|
|
|
Hannoskaj
Forum Guru
Arimaa player #3794
Gender:
Posts: 75
|
|
Re: Haizhi's unconnected-step pruning (my notes)
« Reply #17 on: Feb 27th, 2009, 5:46am » |
Quote Modify
|
on Feb 27th, 2009, 4:32am, Janzert wrote:
It seems your first position has a related first and second step.
For your first position to move Re3n:
+-----------------+
8| . . . . . . . . |
7| . . . . . . . . |
6| . . x . . x . . |
5| . . . . . . . . |
4| . . . . C e . . |
3| . . x d R R . . |
2| . . . . . . . . |
1| . . . . R . . . |
+-----------------+
a b c d e f g h
Re1n Re2e Ce4w Re3n
|
|
I had thought about keeping the cat from protecting the f3 rabbit, but had forgot about the e1 rabbit. Here is a corrected version with Re1n Rf3e Ce4(wn) Re3n as only solution:
+-----------------+
8| . . . . . . . . |
7| . . . . . . . . |
6| . . x . . x . . |
5| . . . . . . . . |
4| . . . . C e . . |
3| . . x d R R . . |
2| . . . . . c . . |
1| . . . . R . . . |
+-----------------+
a b c d e f g h
Jonas
|
|
IP Logged |
|
|
|
Hannoskaj
Forum Guru
Arimaa player #3794
Gender:
Posts: 75
|
|
Re: Haizhi's unconnected-step pruning (my notes)
« Reply #18 on: Feb 27th, 2009, 5:55am » |
Quote Modify
|
on Feb 26th, 2009, 2:48pm, aaaa wrote:
Bot-assisted analysis bears out that you have succeeded in your goal. Minor corrections are that ha7s md1w eb7e ch7w is actually a goal in three (since rd6w Ee6w Rd5w Cb5s delays the goal for one more move) and that there is one other move that is not a loss in two, eb7e ec7n Rd7w ch7w, but this still loses in three.
See http://arimaa.com/arimaa/learn/notation.html, under "Notation for Recording Arimaa Positions". |
|
Thank you for the correction. I must have seen the defence by Gold with loss in three but did not pay attention since I also knew it went through (just forgot to update length). It would certainly be more aesthetic if there was a way to get rid of it, though.
On the other hand, I had completely missed that the cat b5 could be freed and defend for a turn. In fact I thought I had built everything to make that impossible... Anyway, moving db6 to dc5 in the initial position seems to kill that flaw.
Finally, thank you for the link. I do not call that "agreeable", but with a text file as skeleton, it's at least usable.
Jonas
|
|
IP Logged |
|
|
|
Hannoskaj
Forum Guru
Arimaa player #3794
Gender:
Posts: 75
|
|
Re: Haizhi's unconnected-step pruning (my notes)
« Reply #19 on: Jun 1st, 2009, 1:33am » |
Quote Modify
|
I just had an idea to define unconnected steps, that would avoid making a complete list of tests such as the one at the beginning of the topic :
Four steps are unconnected if all (24) permutations are still legal and yield the same final position.
This does not cover the case:
* support a trap that the second piece to move was supporting
if there is no piece on the trap to die during the move.
Jonas
|
|
IP Logged |
|
|
|
|
Home
Help
Search
Members
Login
Register
Reply
Notify of replies
Send Topic
Print