@Scigatt  
I intended it to be Einstein, though the manestyle got messed up.  
Anyway, since you recognized the light cone, you win!

@furrypony  
Minkowski?

@Seriff Pilcrow  
no

@furrypony  
The green pony’s hard!
 
Um, his/her cutie mark is a double cone with arrows on it. Could it be Apollonius of Perga or Menaechmus?

@mathprofbrony  
I checked this paper, to find who’s that mathematician you mentioned.  
G. E. Andrews, H. Gupta, or Ø. J. Rødseth?

I once knew a mathematician who generalized something called the binary partition function to the m-ary partition functions. His wife was named Mary and he always joked that she thought they were named for her.

@Seriff Pilcrow  
Pale Current is an OC I made. The green pony not Pale Current.  
The pink one is indeed Ada Lovelace. The manestyle should match if you look closely.  

@furrypony
 
I’m going to go out on a limb and say the pink pony is Ada Lovelace. She worked on Charles Babbage’s Analytical Engine, and Babbage himself showed Lovelace a prototype of the Difference Engine. The real Ada Lovelace took interest in the Difference Engine! and as stated by Parcly Taxel, the pink pony is thinking about the Difference Engine.
 
Someone in deviantART said, “The green one looks like Pale Current,” but I don’t understand what “pale current” means.

@Parcly Taxel  
You win!  
So who’s the pink pony?  
For bonus points, who’s the green pony?

@yrfoxtaur It is Babbage’s famous Difference Engine, the most grandiose mechanical computer ever built (albeit in the 1990s by the British Museum). It has about the same computational capabilities as a modern 10-digit scientific calculator.
 
The Engine could only handle in a single operation a unary polynomial; its perceived utility springs from the fact that many important functions in the sciences have good polynomial approximations. Babbage, unfortunately, could not procure the necessary machining time and finances in his lifetime.
 
(S.P. Arity is one of my favourite programming constructs. My Kinross library, for example, uses it to distinguish between different types of path segments).

Heh, nice. Way to play with expectations.

XKCD comic, like most anything, can be improved by clever use of ponies.  
Q.E.D.

Math it can be funny… okay no not really.

is that machine in the domino pony’s thought bubble what i think it is?
 
a harmonic analyzer?

I thought she lost her license because of this.