Milnor's Theorem
If a Compact Manifold 
has Nonnegative Ricci Curvature, then its Fundamental Group has at mostPolynomial growth. On the other hand, if has Negative curvature, then its Fundamental Group hasexponential growth in the sense that 
grows exponentially, where is (essentially) the number ofdifferent ``words'' of length 
which can be made in the Fundamental Group.
References
Chavel, I. Riemannian Geometry: A Modern Introduction. New York: Cambridge University Press, 1994.
- Mersenne Number
- Mersenne Prime
- Mertens Conjecture
- Mertens Constant
- Mertens Function
- Mertens Theorem
- Mertz Apodization Function
- Mesh Size
- Mesokurtic
- M-Estimate
- Metabiaugmented Dodecahedron
- Metabiaugmented Hexagonal Prism
- Metabiaugmented Truncated Dodecahedron
- Metabidiminished Icosahedron
- Metabidiminished Rhombicosidodecahedron
- Metabigyrate Rhombicosidodecahedron
- Metadrome
- Metagyrate Diminished Rhombicosidodecahedron
- Metalogic
- Metamathematics
- Method
- Metric
- Metric Entropy
- Metric Equivalence Problem
- Metric Space