What is the largest program that has been proven correct?<p>We&#x27;re writing programs that are tens of millions of lines of code (OSes, databases, air traffic control systems).  My impression of provable correctness is that the largest program that has been proven is in the area of 100,000 lines (feel free to correct if I am in error).  We need to be able to prove programs two orders of magnitude bigger than that; provable correctness has not been tried for such programs because nobody wants to wait a generation or two before they get the results.