Hi!
I wanted to submit some theory I developed following the topology theory
in IsarMathLib. It deals with some concrete topological spaces
and first some theory of cardinals (necessary for topological spaces).
I did my best to follow your proof style, but I'm not used to it and in
some proofs I did not follow it. Now that is all
proven, I'm rewriting it to follow the style.
The html resulted is the following:
https://belenus.unirioja.es/~daconcep/archivos/Topology_ZF_examples.html
Best regards,
Daniel de la Concepción Sáez