Math & Science ⇒ \rightdasharrow vs. \dashrightarrow

[user49915]

amsfonts has \dashrightarrow (which is \mathrel), whereas unicode-math (with stix/xits) has \rightdasharrow (which is \mathord). Moreover, there are slight differences in the form of the symbol.

As far as my documents are concerned, I cannot imagine that I will ever use the two kinds of arrows simultaneously. I wonder whether there was any rationale for having created a new macro rather than simply replaced the definition of the old one.

Any, by the way, should not the notation X⇢Y simply denote the set of partial maps from X to Y and thus ⇢ be a binary OPERATOR (rather than a relation)? The same goes for the normal (not dashed) arrow →. Have there been any contexts in which → and ⇢ have been used as relations?

Crosspost: http://tex.stackexchange.com/questions/ ... rightarrow