[Haskell-cafe] Derive ET from DN in calculus of constructions

[Dmitriy Matrosov]

Thank you all for the hints and links to many interesting materials!

Well, I've understood, that I need to learn more about constructive
logic and natural deduction. That book was not too detailed on these
topics and authors write only strictly necessary info and from the
wording I understand, they assume the readers are familiar with
natural deduction at least (but I'm not). So now I'm reading some
lectures on these topics and then will try the proof again. Thanks for
the help!