“… such that(,) for every person, there were two chairs.” Should there be a comma after *that*?

Question

In my field of study, I often see statements such as, "... such that, for every person, there were two chairs."

I'm wondering if there should be a comma after "such that"? If so, what are the rules of punctuation that allow and/or necessitate this?

I would greatly appreciate it if someone could please take the time to clarify this point.

EDIT

The entire context would be similar to the following:

If a, b, and c are real numbers with a < 0, then there is a real number y such that(,) for every real number x, ax^2 + bx + c ≤ y.

Answer 1

I'm American and I can tell you that it's not dialectal. What you are really saying is "such that there were two chairs" with the parenthetical "for every person." So there are two correct ways to write it:

1. ...such that for every person there were two chairs.
2. ...such that, for every person, there were two chairs.

The former is more likely if it's a short sentence and the commas don't make the sentence difficult to decipher or ambiguous. (It may also be more common in America). The latter is more likely if the sentence is long or ambiguous without the commas. In speech you may well hear *"such that for every person, there were two chairs" but it is not correct to write it that way. You can choose to put a comma on both sides of a parenthetical or neither but you can't have one comma.

Answer 2

Yes, a comma goes there.

However, being raised on British English, I cannot speak for other geographic varieties. In American English commas tend to be dropped in places, which would explain the inconsistencies you have observed.

All in all, I think it depends on which English you are learning.