chapter AFP

session Delta_System_Lemma =  "ZF-Constructible" +
  description "
    Cofinality and Delta System Lemma

    We formalize the basic results on cofinality of linearly ordered
    sets and ordinals and Shanin's Lemma for uncountable families of
    finite sets. This last result is used to prove the countable chain
    condition for Cohen posets. We work in the set theory framework of
    Isabelle/ZF, using the Axiom of Choice as needed.
  "
  options [timeout = 600]
  theories
    "Konig"
    "Delta_System"
    "Cohen_Posets"
  document_files
    "root.tex"
    "header-delta-system.tex"
    "multidef.sty"
    "root.bib"
    "root.bst"
