Church-Turing Thesis
The Turing Machine concept defines what is meant mathematically by an algorithmic procedure. Stated another way, afunction 
is effectively Computable Iff it can be computed by a Turing Machine.
References
Penrose, R. The Emperor's New Mind: Concerning Computers, Minds, and the Laws of Physics. Oxford, England: Oxford University Press, pp. 47-49, 1989.
- Cyclotomic Integer
- Cyclotomic Invariant
- Cyclotomic Number
- Cyclotomic Polynomial
- Cylinder
- Cylinder Cutting
- Cylinder-Cylinder Intersection
- Cylinder Function
- Cylinder-Sphere Intersection
- Cylindrical Coordinates
- Cylindrical Equal-Area Projection
- Cylindrical Equidistant Projection
- Cylindrical Function
- Cylindrical Harmonics
- Cylindrical Hoof
- Cylindrical Projection
- Cylindrical Segment
- Cylindrical Wedge
- Cylindroid
- Daisy
- d'Alembertian Operator
- d'Alembert Ratio Test
- d'Alembert's Equation
- d'Alembert's Solution
- d'Alembert's Theorem