Formally speaking, the bug in the compiler does not take into account the

“!” (not) operator in context of equal checks.

In the bogus environment of ml compiler, truth equation of “!” is changed.

From the same line of code, we have a different logic result.

Trusting the source code is now an error. The real logic is masked by the bug.

Some of the slides seem a little wonky with overwritten text, but mostly comprehensible.

source: L