For starters, it would be nice to be able to make trivial manipulations of algebraic expressions involving real numbers not incredibly tedious. As far as I kno

For starters, it would be nice to be able to make trivial manipulations of algebraic expressions involving real numbers not incredibly tedious. As far as I know no existing proof assistant is up to that challenge. Again, it's not a matter of power--many, many proof assistants can formalize the vast majority of mathematics--it's about UX.