Checking multiplex patterns
When you check multiplex patterns there should be two numbers under
any multiplex throws and as before one number under every other throw.
The pattern will be a valid juggling pattern if one of the two numbers
under each multiplex throw is a 2 or a 1. An example should help.
To check that 23 is a valid pattern, first write 4 under the
throw four beats after the 4.
Note that the 3 within the square brackets is on the same beat
as the 4, so the 2 is one beat later, the other 3 is two beats later, there
is another multiplex throw three beats later, so the 2 is four beats later.
Now write 3 under the throw three beats after the multiplexed 3.
Now write 2 under the throw two beats after the 2.
Now write 3 under the throw three beats after the final 3.
There are two numbers under the multiplex throw, one of which is
a 2 and there is one number under every other throw in the pattern, so
23 is a valid pattern.
Reading the checking numbers in reverse in multiplex patterns would lead to patterns where you have to catch two balls at once.