The theorem c_pos asserts that the RS-native speed of light satisfies c_rs > 0.
Proof proceeds in two steps. First apply c_rs_eq_one to obtain the equality c_rs = 1. Then norm_num reduces the goal 1 > 0 to a trivial numerical fact.
The underlying definitions are c_rs := ℓ₀ / τ₀ together with the RS-native assignments ℓ₀ = 1 and τ₀ = 1 (both set to unity by definition of the fundamental scales). Hence c_rs = 1 follows immediately by division, and positivity is immediate from the ordering on ℝ.