A related report from way back, that counts expressions instead of symbols[0]. The counting procedure used in OP's referenced table might benefit from first extracting expressions, and then counting individual symbol frequencies.
[0]: Watt, S. M. A Preliminary Report on the Set of Symbols Occurring in Engineering Mathematics Texts. In Proceedings of MICA 2008: Milestones in Computer Algebra 2008.
No, the data (as described in So's thesis) was mathematical expressions extracted from TeX source code, so the surrounding text and email addresses etc. were ignored. Skimming through by eye I can't see @ in any of So's tables, and searching for the hex Unicode value the tables list for every other character yields no hits: @ is not in the tables.
∋ is there anomalously frequently, and @ is missing, so something seems to have gone wrong, probably at multiple stages in the pipeline.
I had a bit of a chuckle that apparently 5 out of 50000 opening "(" parentheses weren't closed, but then I saw that 2 out of 12000 "]" brackets weren't opened! What criminal is using these standalone?
Mixing them should be relatively common when denoting intervals, as in "(a, b]" or "[a, b)", so that'd be one cause for being unbalanced. But even so, the math on their usage still doesn't add up.
A related report from way back, that counts expressions instead of symbols[0]. The counting procedure used in OP's referenced table might benefit from first extracting expressions, and then counting individual symbol frequencies.
[0]: Watt, S. M. A Preliminary Report on the Set of Symbols Occurring in Engineering Mathematics Texts. In Proceedings of MICA 2008: Milestones in Computer Algebra 2008.
It seems weird that ∋ would be the sixth-most frequent symbol, while ∈ doesn't figure at all.
Agreed. Even stranger to me is @ as the fourth most common operator, supposedly more common than +. The whole thing seems dubious.
The table byline says: "The @ symbol is used to encode mathematical formulas for the computer. It is not visible to the user."
I would suspect that the @ comes from author email addresses. It's not entirely wrong to call that an operator. ;)
No, the data (as described in So's thesis) was mathematical expressions extracted from TeX source code, so the surrounding text and email addresses etc. were ignored. Skimming through by eye I can't see @ in any of So's tables, and searching for the hex Unicode value the tables list for every other character yields no hits: @ is not in the tables.
∋ is there anomalously frequently, and @ is missing, so something seems to have gone wrong, probably at multiple stages in the pipeline.
Do papers tend to have more email addresses or more plus signs? I'd expect the latter, by a lot.
I had a bit of a chuckle that apparently 5 out of 50000 opening "(" parentheses weren't closed, but then I saw that 2 out of 12000 "]" brackets weren't opened! What criminal is using these standalone?
Probably not this, but J uses lonely brackets and braces as standalone operators: https://code.jsoftware.com/wiki/NuVoc.
There is the normal notation for half-open ranges, which would lead to unbalanced brackets.
Mixing them should be relatively common when denoting intervals, as in "(a, b]" or "[a, b)", so that'd be one cause for being unbalanced. But even so, the math on their usage still doesn't add up.
You won't like bra-ket notation then :)