FoundationsLesson 05 / 09
Helpful does not mean trusted.
is an architectural role, not an accusation. Helpers can be useful and well tested while having no authority to declare a proof valid.
1. Imagine a buggy builder
A builder could accidentally use an assumption from another branch or invent a reference that was never introduced.
The must reject the candidate regardless of the builder’s confidence. never grants acceptance.
2. Automation owes us evidence
Future tactics and search will return ordinary , checked by the same process as handwritten candidates.
Pretty printers and lessons can explain the result, but their display is not the source of its validity. A failed search is only a failed attempt.
3. Take this with you
Convenience can grow without expanding the trusted kernel. Helpers produce evidence; the kernel judges it.