Talk:hypoelliptic operator

To "preserve smoothness" would mean that if u is smooth, then Pu is smooth. But the Wikipedia article says the converse: if Pu is smooth, then u is smooth: this is more like saying that P^-1 preserves smoothness. —AugPi 16:02, 4 June 2009 (UTC)

I honestly have no idea what you just wrote. THis definition was composed at the issue of a fairly lengthy [1] at WIkipedia's WikiProjects Mathematics. I can only assume what you're saying is what one of the comments said: "'preserves smoothness' is not very clear; but maybe this is the best one can expect from a dictionary. (Rather, the inverse operator preserves smoothness)." Circeus 20:46, 4 June 2009 (UTC)