There is a interactive web toy for sequent calculus proofs here: http://logitext.mit.edu/main http://logitext.mit.edu/main For natural deduction and other topi

There is a interactive web toy for sequent calculus proofs here: http://logitext.mit.edu/main http://logitext.mit.edu/main For natural deduction and other topics, Bob Atkey's interactive course is fun: https://personal.cis.strath.ac.uk/robert.atkey/cs208/index.html https://personal.cis.strath.ac.uk/robert.atkey/cs208/index.h...