I feel like this is multiple functions in a trench coat

def decrease_strict(ms, element, count)
def decrease_lax(ms, element, count)
def delete_strict(ms, element)
def delete_lax(max, element)

As far as I know no and I don’t think there would be ever support for that not only in the documentation, but also in Elixir itself. The compiler should warn you that functions with the same name and arity should be grouped together.

You can give different names to all related functions. for example by simply adding _lax suffix and then you can group specific functions. For more information take a look at:
Grouping functions, types, and callbacks | mix docs task @ ex_doc documentation

Definitely, it should otherwise this be reported as a bug

To be technically correct (the best kind of correct) these are two separate functions: delete/2 and delete/3. When we say that arity is part of the function name, this is very literal. Elixir makes it possible to not group them though this is this more of a quirk of its syntax (and as mentioned it emits a warning and most people compile with --warnings-as-errors). In Erlang this isn’t even possible:

1> foo("A") -> "You said 'A'"; foo(N) -> "You didn't say 'A'".
ok
2> bar("A", "B") -> "You said 'A'"; bar(N) -> "You didn't say 'A'".
* 1:15: syntax error before: '->'