formally verified?
In high-school maths, we are introduced to the idea of a
proof — the word “proof” is etymologically related to the word “probe”. In a proof, we reason from first principles (aka
axioms), why a certain assertion (aka
theorem) holds true. Said differently, we
verify the theorem, and
proof represents the verification process.
The axioms and the proof need a language in which they are represented — at a minimum, this language involves a syntax and a set of
proof rules governing that syntax. This mathematical rule-based verification is also called
formal verification, to distinguish it from the colloquial use of the word verification which may just involve human inspection.