# So that and such that

1. May 31, 2009

### lolgarithms

"so that" and "such that"

Have a question about usage of mathematical jargon...
what are the differences between usage of "so that" and "such that"?

"z is a complex number such that Re[z]>0.": correct
"z is a complex number so that Re[z]>0.": wrong

"Define z so that Re[z]>0"
"Define z such that Re[z]>0"

2. May 31, 2009

### AUMathTutor

Re: "so that" and "such that"

Perhaps someone has a more technical answer than this, but...

For me, "such that" means something is already a certain way and you're describing it, whereas so that means that something isn't a certain way already, but you're prescribing it. For instance...

"You have to study *so that* you will pass the test."
"You read a book *such* that it's 20 pages long."

Like, "so that" is a means to an end, and "such that" is just how it is.

I apologize if this isn't right. Somebody will be along to correct me.

In English, the difference between "so that" and "such that" is a much easier one to make, but I'm not sure it carries into the realm of mathematics. "such" is a word derived from "so much". "Such" deals with quantities, whereas "So" deals with qualities.

3. May 31, 2009

Re: "so that" and "such that"

I looked up "such that" in the Collins concise English dictionary and the definition was:used to express purpose or result."So that",however, was adjacent to "such that" but not in bold type.It seems from this that either usage is correct.When I looked for
"so that" it wasn't entered.Because of the emphasis in the dictionary it seems that "such that" is the preferred usage.I,also,apologise if this isn't right.

4. May 31, 2009

### matt grime

Re: "so that" and "such that"

"So" means "hence" - there should be a deduction: we choose X so that Y is true.

Or something like that, anyway. 'Such that' can also be used to mean 'satisfying' where it wouldn't be sensible to use 'so that'.

Last edited: May 31, 2009
5. May 31, 2009

### Enuma_Elish

Re: "so that" and "such that"

"Define z so that Re[z]>0": correct

"Define z such that Re[z]>0": incorrect

"Suppose there exists a complex number z such that Re[z]>0": correct

"Suppose there exists a complex number z so that Re[z]>0": incorrect

6. May 31, 2009

### HallsofIvy

Staff Emeritus
Re: "so that" and "such that"

Grammatically, "such that" applies to a noun, "so that" applies to a verb. I believe that is also what Enuma Elish is saying.

7. May 31, 2009

### lolgarithms

Re: "so that" and "such that"

im kinda confused because of different explanations

also, you can say "z is defined so that Re[z] > 0"
in other words, "so that" indicates an end, a purpose while such that just describes
does this sum up the correct usage?

Last edited: May 31, 2009
8. May 31, 2009

Re: "so that" and "such that"

Well there does seem to be confusion here and perhaps we are being too fussy.How about an alternative, for example......Z is defined in such a way that etc

9. May 31, 2009

### symbolipoint

Re: "so that" and "such that"

"Such" seems to have a quality like a relative pronoun which can be used in combination with "that", working as a conjunction. HallsOfIvy gave the briefest and most useful characterisation. The "such" involved can be an idea having no concrete existance.