Zulip Chat Archive
Stream: Is there code for X?
Topic: pow left is injective for reals
Snir Broshi (Oct 07 2025 at 22:01):
theorem foo (n : ℕ) (hn : n ≠ 0) (x y : ℝ) (hx : 0 ≤ x) (hy : 0 ≤ y) :
x ^ n = y ^ n ↔ x = y := by
sorry
theorem bar (r : ℝ) (hr : 0 < r) (x y : ℝ) (hx : 0 ≤ x) (hy : 0 ≤ y) :
x ^ r = y ^ r ↔ x = y := by
sorry
Do these exist, or does anyone have counterexamples?
I found a similar theorem for HPow.hPow ℕ ℕ ℕ: docs#Nat.pow_left_injective
Damiano Testa (Oct 07 2025 at 22:06):
Maybe docs#Real.rpow_left_inj ?
Damiano Testa (Oct 07 2025 at 22:07):
simp_all proves the first.
Damiano Testa (Oct 07 2025 at 22:10):
In fact, pow_left_inj₀ hx hy hn proves the first and Real.rpow_left_inj hx hy hr.ne' proves the second.
Last updated: Dec 20 2025 at 21:32 UTC