Fundamental System
A set of Algebraic Invariants for a Quantic such that any invariant of the Quanticis expressible as a Polynomial in members of the set. In 1868, Gordan proved the existence of finite fundamental systemsof algebraic invariants and covariants for any binary Hilbert 
(1890) proved theHilbert Basis Theorem, which is a finiteness theorem for the related concept of Syzygies.
References
Hilbert, D. ``Über die Theorie der algebraischen Formen.'' Math. Ann. 36, 473-534, 1890.
- Semiminor Axis
- Semiperfect Magic Cube
- Semiperfect Number
- Semiperimeter
- Semiprime
- Semiprime Ring
- Semiregular Polyhedron
- Semiring
- Andrews-Curtis Link
- Andrews-Schur Identity
- Andrew's Sine
- Andrica's Conjecture
- André's Problem
- André's Reflection Method
- Anger Function
- Angle
- Angle Bisector
- Angle Bisector Theorem
- Angle Bracket
- Angle of Parallelism
- Angle Trisection
- Angular Acceleration
- Angular Defect
- Angular Distance
- Angular Velocity