Dedekind Cut
A set partition of the Rational Numbers into two nonempty subsets 
and 
such that allmembers of are less than those of and such that has no greatest member. Real Numbers can be defined using either Dedekind cuts or Cauchy Sequences.
References
Courant, R. and Robbins, H. ``Alternative Methods of Defining Irrational Numbers. Dedekind Cuts.'' §2.2.6 in What is Mathematics?: An Elementary Approach to Ideas and Methods, 2nd ed. Oxford, England: Oxford University Press, pp. 71-72, 1996.
- Exmedian Point
- Exogenous Variable
- Exotic R4
- Exotic Sphere
- Exp
- Expansion
- Expansive
- Expectation Value
- Experimental Design
- Exploration Problem
- Exponent
- Exponential Digital Invariant
- Exponential Distribution
- Exponential Divisor
- Exponential Function
- Exponential Function (Truncated)
- Exponential Inequality
- Exponential Integral
- Exponential Map
- Exponential Matrix
- Exponential Ramp
- Exponential Sum Formulas
- Exponential Sum Function
- Exponent Laws
- Exponent Vector