For 10 points, identify this statement, also known as subadditivity, which says that the length of any side of an eponymous shape must be less than or equal to the sum of the other two sides.
The p-adic numbers satisfy a strong version of this statement, and a reversed form of it holds for non-positive definite metric spaces, such as a Minkowski space. A more general version of this statement was discovered by Bunyakovsky in its integral form. It is not obeyed by the L-0 norm, but it is a special case of the Cauchy-Schwartz inequality for the Euclidian norm. For 10 points, identify this statement, also known as subadditivity, which says that the length of any side of an eponymous shape must be less than or equal to the sum of the other two sides.
The p-adic numbers satisfy a strong version of this statement, and a reversed form of it holds for non-positive definite metric spaces, such as a Minkowski space.
Triangle Inequality [prompt on Cauchy-Schwarz Inequality before mentioned]