They are adjoints. http://www.reproducibility.org/RSF/book/gee/ajt/paper_html/index.html http://www.reproducibility.org/RSF/book/gee/ajt/paper_html/i... I have

They are adjoints. http://www.reproducibility.org/RSF/book/gee/ajt/paper_html/index.html http://www.reproducibility.org/RSF/book/gee/ajt/paper_html/i... I have written something on adjoints, they are literally everywhere https://github.com/adamnemecek/adjoint https://github.com/adamnemecek/adjoint