session Myhill in "Journal" = HOL +
  options [document = false]
  theories 
    "../Folds"
    "../Regular_Set"
    "../Regular_Exp"
    "../Derivatives"
    "../Myhill_1"
    "../Myhill_2"
    "../Myhill"
    "../Closures"
    "../Closures2"
    "../Attic/Prefix_subtract"
session Journal in "Journal" = Myhill +
  options [document = pdf, document_output = "..", document_variants = "journal"]
  theories
    "Paper"
session Slides6 in "Slides" = Myhill +
  options [document = pdf, document_output= "..", document_variants = "slides6"]
  theories
    "Slides6"