# Mathematical notation question: what does this mean? **URL:** \ **Category:** Factual Questions\ **Created:** [November 4, 2008, 12:28am UTC](https://boards.straightdope.com/t/mathematical-notation-question-what-does-this-mean/470953 "2008-11-04T00:28:34Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [November 4, 2008, 12:28am UTC](https://boards.straightdope.com/t/mathematical-notation-question-what-does-this-mean/470953/1 "2008-11-04T00:28:34Z")
There’s a portrait that I walk by occasionally here that depicts a dead white guy standing in front of a chalkboard with an equation on it. I don’t recognize the equation, and I wonder what it means. The equation is y{x}^n = y{x}_0^n + y{x}_\infty^n, and this is in the engineering school, if that helps to narrow it down. ---
**Author:** ![Spectre\_of\_Pithecanthropus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spectre_of_pithecanthropus/32/12343_2.png) [@Spectre\_of\_Pithecanthropus](https://boards.straightdope.com/u/Spectre_of_Pithecanthropus)\ **Post date:** [November 4, 2008, 12:35am UTC](https://boards.straightdope.com/t/mathematical-notation-question-what-does-this-mean/470953/2 "2008-11-04T00:35:53Z")
Based on what I know of you, you know a lot more math than I do, so I probably can’t tell you anything you haven’t already guessed. But in case you’re having an off day and overlooked it… I assume the ^n is “raised to the nth power”. I’ve seen the backwards slash used to mean “is divisible by”, but it doesn’t make much sense inside the curly braces. Maybe it has something to do with cardinality of sets? That’s all I got. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [November 4, 2008, 12:50am UTC](https://boards.straightdope.com/t/mathematical-notation-question-what-does-this-mean/470953/3 "2008-11-04T00:50:25Z")
I don’t know LaTeX, but that would be my first guess about the backslashes. I know that LaTeX uses them to denote things magical to itself. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [November 4, 2008, 12:55am UTC](https://boards.straightdope.com/t/mathematical-notation-question-what-does-this-mean/470953/4 "2008-11-04T00:55:25Z")
Yeah, that’s LaTeX. I figure it’s a safe bet that anyone who would recognize the equation also knows LaTeX. ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [November 4, 2008, 1:26am UTC](https://boards.straightdope.com/t/mathematical-notation-question-what-does-this-mean/470953/5 "2008-11-04T01:26:19Z")
I haven’t really done anything with LaTeX in a while, but on the off-chance somebody without a LaTeX background knows the equation in question, I think it’s something like y{x}[sup]n[/sup] = y{x}[sub]0[/sub][sup]n[/sup] + y{x}[sub]∞[/sub][sup]n[/sup], right? Otherwise, I’m stumped – I don’t know curly brackets in any other context than denoting sets. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [November 4, 2008, 1:50am UTC](https://boards.straightdope.com/t/mathematical-notation-question-what-does-this-mean/470953/6 "2008-11-04T01:50:59Z")
Yeah, that’s my reading of the L[sup]A[/sup]T[sub]E[/sub]X, too. But I can’t help with the equation itself. ---
**Author:** ![Santo\_Rugger](https://avatars.discourse-cdn.com/v4/letter/s/e95f7d/32.png) [@Santo\_Rugger](https://boards.straightdope.com/u/Santo_Rugger)\ **Post date:** [November 4, 2008, 2:11am UTC](https://boards.straightdope.com/t/mathematical-notation-question-what-does-this-mean/470953/7 "2008-11-04T02:11:56Z")
Is it a summation? In other words all the x[sub]subs[/sub] add up to the main function? ---
**Author:** ![NinetyWt](https://avatars.discourse-cdn.com/v4/letter/n/cc9497/32.png) [@NinetyWt](https://boards.straightdope.com/u/NinetyWt)\ **Post date:** [November 4, 2008, 3:22am UTC](https://boards.straightdope.com/t/mathematical-notation-question-what-does-this-mean/470953/8 "2008-11-04T03:22:23Z")
Reminds me of some kind of series or sequence.