Date: Tue, 21 Dec 93 09:13:38 +0800
From: Mr Anand Rao <anandrao@hk.super.net >

Your concept is theoretically extendable to the 10*10 tangle, but even
with this optimisation the puzzle would take a long time to solve. How
long do you take for the 5*5 Tangle on your computer?

```On Mon, 20 Dec 1993, Jan de Ruiter wrote:
```

To: cube-lovers@ai.mit.edu
Subject: Re: Search order of Tangle

I saw the discussion of Dale and Don about the search order
(fillpattern) for rubiks tangle come by, and wondered why they both
missed an even better search order (the best?):

```Don:		 Dale:            Jan:              Equivalent to:
1  3  5  7  9    1  2  6 10 15    1  2  5 10 17    17 16 15 14 13
2  4  6  8 10    3  4  7 11 16    3  4  6 11 18    18  5  4  3 12
11 12 13 14 15    5  8 12 17 20    7  8  9 12 19    19  6  1  2 11
16 17 18 19 20    9 13 18 21 23   13 14 15 16 20    20  7  8  9 10
21 22 23 24 25   14 19 22 24 25   21 22 23 24 25    21 22 23 24 25

The number of constraints is illustrative:
don:  0 1 1 2 1 2 1 2 1 2 1 2 2 2 2 1 2 2 2 2 1 2 2 2 2
dale: 0 1 1 2 1 1 2 2 1 1 2 2 2 1 1 2 2 2 2 2 2 2 2 2 2
jan:  0 1 1 2 1 2 1 2 2 1 2 2 1 2 2 2 1 2 2 2 1 2 2 2 2
```

I disliked the irregularity in both don and dales search orders, and
in search for a more regular order, I found this one, which is better.
It is readily extendible to the 10 by 10 tangle.

- Jan D. de Ruiter