rename 'extensions' section file; add reference to Löb's paper

docs/bib.bib

@@ -3836,3 +3836,16 @@ year = {2013}
 	journal={Submitted to JFP},
         year  = {2017},
 }
+
+@article{Loeb,
+ ISSN = {00224812},
+ URL = {http://www.jstor.org/stable/2266895},
+ author = {Martin H. Löb},
+ journal = {The Journal of Symbolic Logic},
+ number = {2},
+ pages = {115--118},
+ publisher = {Association for Symbolic Logic},
+ title = {Solution of a Problem of Leon Henkin},
+ volume = {20},
+ year = {1955}
+}

docs/ghost-state.tex → docs/extended-logic.tex

@@ -41,8 +41,8 @@ We collect here some important and frequently used derived proof rules.
   {\TRUE \proves \plainly\TRUE}
 \end{mathparpagebreakable}
 
-Noteworthy here is the fact that Löb induction can be derived from $\later$-introduction and the fact that we can take fixed-points of functions where the recursive occurrences are below $\later$.%
-\footnote{See \url{https://en.wikipedia.org/wiki/L\%C3\%B6b\%27s_theorem}.}
+Noteworthy here is the fact that Löb induction can be derived from $\later$-introduction and the fact that we can take fixed-points of functions where the recursive occurrences are below $\later$~\cite{Loeb}.%
+\footnote{Also see \url{https://en.wikipedia.org/wiki/L\%C3\%B6b\%27s_theorem}.}
 Furthermore, $\TRUE \proves \plainly\TRUE$ can be derived via $\plainly$ commuting with universal quantification ranging over the empty type $0$.
 To derive that existential quantifiers commute with separating conjunction requires an intermediate step using a magic wand: From $P * \exists x, Q \vdash \Exists x. P * Q$ we can deduce $\Exists x. Q \vdash P \wand \Exists x. P * Q$ and then proceed via $\exists$-elimination.
 

docs/iris.tex

@@ -56,7 +56,7 @@ For a list of changes in Iris since then, please consult our changelog at \url{h
 \input{model}
 \endgroup
 \clearpage\begingroup
-\input{ghost-state}
+\input{extended-logic}
 \endgroup
 \clearpage\begingroup
 \input{language}