Lattice paths and determinants

TODO

• Lemma
  • proof
• Theorem
  • proof

There is a lengthy attempt to at this chapter version of the lean3 version here: https://github.com/mo271/FormalBook/blob/92f57b44cbbc1cd02ca77994efe8d8e6de050a19/src/chapters/32_Lattice_paths_and_determinants.lean