Relation
A relation is any Subset of a Cartesian Product. For instance, a Subset of 
, called a(binary) ``relation from 
to 
,'' is a collection of Ordered Pairs 
with firstcomponents from and second components from , and, in particular, a Subset of 
is called a``relation on .'' For a binary relation 
, one often writes 
to mean that is in .
- Schinzel's Theorem
- Schisma
- Schlegel Graph
- Schläfli Double Six
- Schläfli Function
- Schläfli Integral
- Schläfli Polynomial
- Schläfli's Formula
- Schläfli's Modular Form
- Schläfli Symbol
- Schlömilch's Function
- Schlömilch's Series
- Schmitt-Conway Biprism
- Schnirelmann Constant
- Schnirelmann Density
- Schnirelmann's Theorem
- Schoenemann's Theorem
- Scholz Conjecture
- Schoolgirl Problem
- Schoute Coaxal System
- Schoute's Theorem
- Schrage's Algorithm
- Schroeder Stairs
- Schröder-Bernstein Theorem
- Schröder Number