I have a question about commutators. Can someone explain what the digits stand for when it for example look like this [4.3] or [3.1].
There are lots of explanations of this commutator notation across many threads going back years.
In brief, [4,3] is short-hand to describe the general structure / length of a commutator. A commutator is a sequence of the form X Y X' Y' and the [4,3] short-hand says that X is 4 moves and Y is 3 moves.
The other notation we use is [N:M] where a ":" is used instead of a ",". This is for conjugate sequences (setup moves) and those sequences are of the form X Y X'. So [1:1] is a sequence where X and Y are both one move.
If you assume a [4,3] sequence is made up of nested commutators and conjugates then the only form it could be is [[1,1],[1:1]] (14 moves total).