One of the basic theorems in universal algebra is Birkhoff's variety theorem: the smallest equationally axiomatizable class containing a class K of algebras coincides with the class obtained by taking ...

Polygons are multi-sided shapes with different properties. Shapes have symmetrical properties and some can tessellate. Loci and constructions - Edexcel Loci are a set of points with the same property.

The theorems of Hadamard and of Poincaré–Miranda give sufficient conditions for the existence of at least one zero for some continuous mappings from a Euclidean space into itself. The note gives ...