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Description: Define the function for the norm of a vector of Hilbert space. See normval for its value and normcl for its closure. Theorems norm-i-i , norm-ii-i , and norm-iii-i show it has the expected properties of a norm. In the literature, the norm of A is usually written "|| A ||", but we use function notation to take advantage of our existing theorems about functions. Definition of norm in Beran p. 96. (Contributed by NM, 6-Jun-2008) (New usage is discouraged.)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | df-hnorm | |- normh = ( x e. dom dom .ih |-> ( sqrt ` ( x .ih x ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 0 | cno | |- normh |
|
| 1 | vx | |- x |
|
| 2 | csp | |- .ih |
|
| 3 | 2 | cdm | |- dom .ih |
| 4 | 3 | cdm | |- dom dom .ih |
| 5 | csqrt | |- sqrt |
|
| 6 | 1 | cv | |- x |
| 7 | 6 6 2 | co | |- ( x .ih x ) |
| 8 | 7 5 | cfv | |- ( sqrt ` ( x .ih x ) ) |
| 9 | 1 4 8 | cmpt | |- ( x e. dom dom .ih |-> ( sqrt ` ( x .ih x ) ) ) |
| 10 | 0 9 | wceq | |- normh = ( x e. dom dom .ih |-> ( sqrt ` ( x .ih x ) ) ) |