Collation algorithms are ultimately about sorting and normalization algorithms are ultimately about equality. There is a direct overlap because if your collatio

Collation algorithms are ultimately about sorting and normalization algorithms are ultimately about equality. There is a direct overlap because if your collation algorithm doesn't agree with your normalization algorithm you get subtle sorting bugs. I believe in this case things are handled by the collation algorithms all depending on a specific normalization form for input and the dependency arrow pointing that way. But there's a case to be made that the dependency arrow makes just as much sense pointing the other direction, and the proliferation of collation algorithms a likely indicator that language/collation-specific normalization is still a possible overlooked need. There's not really a specific right answer here, and the current dependency arrow makes sense from a simplicity standpoint, whether or not it is a perfect abstraction of the problem domain. There are known gaps, which is why Unicode is up to four different normalization algorithms today.