A nice feature of LSD is to allow users to specify the range of the dates in case of uncertainty. So you have b(x,y) for date range (x,y); u(x) for (-inf, x) and l(x) for the range (x,+inf). While this is OK, I think this notation of b, u, l is not intuitive and quite difficult to remember.

Why not just use the same math notation I wrote above?

An even easier solution for biologists (who are not mathy) is to use the range notation in R, because many biologists nowadays know R:

You can extend this format, say x: or x:NA if the upper bound is +inf and :y or NA:y if the lower bound is -inf. (NA for not available).

I prefer this format, which is more user-friendly.

What do you think? It is possible to implement this in LSD?

Perhaps you can still allow the b, u, l notation at the same time, for backward compatibility.