because it's simply not cost effective for the majority of software. That's a great point. We utilize best practices, like automated tests, to narrow the gap

because it's simply not cost effective for the majority of software. That's a great point. We utilize best practices, like automated tests, to narrow the gap between pure experimentation and mathematical proof. Proofs in most code would be difficult to impossible because most of use libraries that use other libraries, etc., so we just do the best we can given the time and monetary constraints that we have.