?? "constant of integration" as "differential galois ambiguity" ?? .... ??? ...

?? "solveableness" ... ??? ....

?? "product integral" ... ????? ......

?? analog for [equation with multiple solutions] of idea that possibility of having to solve [equation with no solutions] is in some sense (and to some extent ...) "protected against" by ... ?? fact that "if it never happens then no one will ever try to reverse it" .... ???? ..... ??? analog as maybe that it's _anti_-protected against ?? ... ???? ....

?? was going to mention "maurer-cartan" here but maybe what i was really trying to get at is simply diff eq for translations on given lie group ... ?? ....

?? analog (wrt discrete : continuous analogy ...) of "lagrange extrapolation" here ?? ....