You need Isabelle2019 to use the Isabelle developments in this directory. You can obtain Isabelle2019 from the Isabelle website.
To make the Isabelle developments in this directory available to your
Isabelle installation, please add the path of this directory to the file
$ISABELLE_HOME_USER/ROOTS. You can find out the value of
$ISABELLE_HOME_USER by running the following command:
isabelle getenv ISABELLE_HOME_USER
Running make builds the PDF documents for the different Isabelle
libraries and places them in $ISABELLE_BROWSER_INFO/Ouroboros. You can
find out the value of $ISABELLE_BROWSER_INFO by running the following
command:
isabelle getenv ISABELLE_BROWSER_INFO
The makefile specifies two targets: properly, which is the default,
and qnd. With properly, fake proofs (sorry) are not accepted; with
qnd, quick-and-dirty mode is used and thus fake proofs are accepted.