Harnack's Theorems
Harnack's first theorem states that a real irreducible curve of order 
cannot have more than
circuits (Coolidge 1959, p. 57).
Harnack's second theorem states that there exists a curve of every order with the maximum number of circuits compatible withthat order and with a certain number of double points, provided that number is not permissible for a curve of lower order(Coolidge 1959, p. 61).
References
Coolidge, J. L. A Treatise on Algebraic Plane Curves. New York: Dover, 1959.
- Unity
- Univalent Function
- Univariate Function
- Univariate Polynomial
- Universal Graph
- Universal Statement
- Universal Turing Machine
- Unknot
- Unknotting Number
- Unless
- Unlesss
- Unmixed
- Unpoke Move
- Unsafe
- Unsolved Problem
- Unstable Improper Node
- Unstable Node
- Unstable Spiral Point
- Unstable Star
- Untouchable Number
- U-Number
- Upper Bound
- Upper Integral
- Upper Limit
- Upper Sum