map_one_ne_zero

∀ {R : Type u_1} [inst : CommRing R] {f : R → ℝ} {c : ℝ},
  f ≠ 0 → 0 ≤ f → (∀ (x y : R), f (x * y) ≤ c * f x * f y) → f 1 ≠ 0

If f : R → ℝ is a nonzero, nonnegative, multiplicatively bounded function, then f 1 ≠ 0.

Defined in: Mathlib.Analysis.Normed.Unbundled.SeminormFromBounded
Cited by: 3 results in Mathlib
Foundations: Depth 101 from the axioms · uses propext, Classical.choice, Quot.sound
Assumes: CommRing

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