[r-t] doubles principle

[edward martin]

On 7/11/06, Alexander Holroyd <holroyd at math.ubc.ca> wrote:
> Here is this week's challenge, folks: find a decent (or even passable)
> extent of the doubles principle 5.1.3.5.1 (5 changes/lead).  How difficult
> can it be - it's only _doubles_?  Nevertheless I haven't been able to do
> it.

As I understand the problem: There are 24 row types in the extent (if
you like the row types can be defined by setting out the 24 rows with
say 5 always in 5ths place)
Your principle has 5 row types in its plain course
Since there are only 24 row types, one cannot set out the extent on
paper as being so many plain course structures because 24 is not
divisible by 5 You could perhaps have 4 plain course structures
containg 20 row types but the remaining 4 row types would be hard to
get  in sets of 5 rows
mew