English
The norm on the space is defined by the real part of the scalar product with itself: ‖x‖ = √(Re ⟪x, x⟫). This defines a (semi)norm coming from the core.
Русский
Норма на пространстве задаётся как ‖x‖ = √(Re ⟪x, x⟫); это (псевдонормированная) норма, порожденная ядром.
LaTeX
$$$\|x\| = \sqrt{\operatorname{Re}\langle x,x\rangle}$$$
Lean4
/-- (Semi)norm constructed from a `PreInnerProductSpace.Core` structure, defined to be the square
root of the scalar product. -/
def toNorm : Norm F where norm x := √(re ⟪x, x⟫)