Algebra over a field Updated +Created
A vector field with a bilinear map into itself, which we can also call a "vector product".
Note that the vector product does not have to be neither associative nor commutative.
Examples: en.wikipedia.org/w/index.php?title=Algebra_over_a_field&oldid=1035146107#Motivating_examples
Cayley-Dickson construction Updated +Created
Constructs the quaternions from complex numbers, octonions from quaternions, and keeps doubling like this indefinitely.
Frobenius theorem (real division algebras) Updated +Created
Octonion Updated +Created
Unlike the quaternions, it is non-associative.