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So that and such that

  1. May 31, 2009 #1
    "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

    but what about this case:

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

    I really can't embarass myself when I write mathematical papers. please help.
  2. jcsd
  3. May 31, 2009 #2
    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.
  4. May 31, 2009 #3
    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.
  5. May 31, 2009 #4

    matt grime

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    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
  6. May 31, 2009 #5
    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
  7. May 31, 2009 #6


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    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.
  8. May 31, 2009 #7
    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
  9. May 31, 2009 #8
    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
  10. May 31, 2009 #9


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    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.
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