• Robbert Krebbers's avatar
    COFE distance is no longer trivial at index 0. · 07d525a0
    Robbert Krebbers authored
    This way we avoid many one-off indexes and no longer need special cases for
    index 0 in many definitions. For example, the definition of the distance
    relation on option and excl has become much easier. Also, uPreds no longer need
    to hold at index 0.
    In order to make this change possible, we had to change the notions of
    "contractive functions" and "chains" slightly.
    Thanks to Aleš Bizjak and Amin Timany for suggesting this change and to help
    with the proofs.