Alternate definition for sup norm
5105
Alternative definition of $\|f\|_{\infty}$ as the smallest of all numbers of the form $\sup\{|g(x)| : x \in X \}$, where $f = g$ almost everywhere
107894
Inequality involving the sup of a function and its first and second derivatives
111475
Uniform convergence and the supremum theorem
1521
Supremum and Infimum
153974
Difference between Norm and Distance
139272
On the norm of a quotient of a Banach space.
114883
Limit definition of pseudoinverse: $A^+ b$ is as close as possible to $y$ in terms of the Euclidean norm $\lVert Ax-b\rVert_2$
73254
spectral radius in normed space is subadditive.
55067
Norm of self-adjoint operator
154226
Upper bound for norm of Hilbert space operator
150415
Pseudoinverse and norm
128558
Inequality between $\ell^p$-norms
7974
lim sup inequality $\limsup ( a_n b_n ) \leq \limsup a_n \limsup b_n $
78654
An example of a norm which can't be generated by an inner product
74501
$\delta : C([0,1])\to\mathbb{R}$, $f\mapsto f(0)$, with sup-norm is bounded but unbounded with one-norm.
76140
The supremum norm is submultiplicative
122305
Proof of matrix norm property: submultiplicativity