
1) Combinatorial game theory
Found on
https://www.crosswordclues.com/clue/surreal-number

In mathematics, the surreal number system is an arithmetic continuum containing the real numbers as well as infinite and infinitesimal numbers, respectively larger or smaller in absolute value than any positive real number. The surreals share many properties with the reals, including a total order ≤ and the usual arithmetic operations (addition,...
Found on
http://en.wikipedia.org/wiki/Surreal_number

A member of a mind-bogglingly vast class of numbers that includes all of the real numbers, all of Georg Cantor's infinite ordinal numbers (different kinds of infinity), a set of infinitesimals (infinitely small numbers) produced from these ordinals, and strange numbers that previously lived outside ...
Found on
http://www.daviddarling.info/encyclopedia/S/surreal_number.html
No exact match found.