# Does the appearance of a unary minus sign where a hyphen belongs result from software packages?

It seems many posters to math.stackexchange.com use software packages that write MathJax code for them (I don't know where they find those things).

And one thing I keep seeing is people writing things like $$\sigma-$$algebra and $$n-$$gon and $$\alpha-$$stable instead of $$\sigma$$-algebra or $$n$$-gon or $$\alpha$$-stable. It has seemed plausible that this was merely another instance of the widespread conspicuous crudity of the level of understanding of typesetting among mathematicians and among posters to this site. But today it occurred to me that maybe something about those software packages that has that result. Does that happen?

• $\sigma-$ algebra: $\sigma-$ algebra, vs. $\sigma$-algebra: $\sigma$- algebra. Mathjax does it too. It all depends on whether one includes the hyphen in the dollar sign, or outside of it. Jul 18 '21 at 21:56
• Let us please try to adopt language which does not serve to perpetuate the stigmatization of mental illness.
– Xander Henderson Mod
Jul 18 '21 at 22:32
• mathpix on $\sigma$-algebra gives $\sigma \text { - algebra. }$ and for $\sigma-$algebra it gives $\sigma \text { -algebra }$ and both are still wrong (extra space). I think the issue is instead either ignorance or apathy (many new papers still write $<x,y>$ for inner products, after all...) Jul 19 '21 at 1:10
• Why would it matter if it was this software which was causing the minus signs? Are you asking this because you have seen a significant amount of improper minus sign usage on the site, and you feel we need to determine the cause of it? Jul 19 '21 at 5:20
• @MikeEarnest : I've seen a lot of it. And I've also seen lots of mathematicians oblivious to things like this. So I don't know whether it's the posters or the software they're using. Jul 19 '21 at 18:11
• @MichaelHardy But you didn't include that in your post. You likely are making a good point, but the hyphen example happens a lot depending on the placement of the dollar signs. I did not mean to minimize your concern, just hoping you can provide, e.g., links to edit histories, or something, relating to your overall concerns. Jul 19 '21 at 18:13

I think the issue is instead either ignorance or apathy (many new papers still write $$$$ for inner products, after all...)
The (mis)use of "$$-$$" instead of a hyphen, or the use of < and > instead of \langle and \rangle (or other more appropriate alternatives) is relatively commonplace, and the best one can do about it, in my opinion, is to politely tell people what the best typographical practices are.