genem: cite our ATVA'19 paper

* doc/spot.bib (baier.19.atva): New reference.
* spot/twaalgos/genem.hh: Cite it.

doc/spot.bib

@@ -31,6 +31,23 @@
   doi		= {10.1007/978-3-642-39176-7_6}
 }
 
+@InProceedings{	  baier.19.atva,
+  author	= {Christel Baier and Franti\v{s}ek Blahoudek and Alexandre
+		  Duret-Lutz and Joachim Klein and David M\"uller and Jan
+		  Strej\v{c}ek},
+  title		= {Generic Emptiness Check for Fun and Profit},
+  booktitle	= {Proceedings of the 17th International Symposium on
+		  Automated Technology for Verification and Analysis
+		  (ATVA'19)},
+  year		= {2019},
+  volume	= {?????},
+  series	= {Lecture Notes in Computer Science},
+  pages		= {???--???},
+  month		= oct,
+  publisher	= {Springer},
+  note		= {To appear}
+}
+
 @InProceedings{	  beer.01.cav,
   author	= {Ilan Beer and Shoham Ben-David and Cindy Eisner and Dana
 		  Fisman and Anna Gringauze and Yoav Rodeh},

spot/twaalgos/genem.hh

@@ -26,6 +26,11 @@ namespace spot
 {
   /// \ingroup emptiness_check_algorithms
   /// \brief Emptiness check of an automaton, for any acceptance condition.
+  ///
+  /// Currently only implemented for twa_graph automata, i.e., not automata
+  /// constructed on-the-fly.
+  ///
+  /// \cite baier.19.atva
   SPOT_API bool
   generic_emptiness_check(const const_twa_graph_ptr& aut);
 
@@ -33,11 +38,16 @@ namespace spot
   /// \brief Accepting run search in an automaton, for any acceptance condition.
   /// \return An accepting run over the automaton, or nullptr if the language is
   /// empty.
+  ///
+  /// Currently only implemented for twa_graph automata, i.e., not automata
+  /// constructed on-the-fly.
   SPOT_API twa_run_ptr
   generic_accepting_run(const const_twa_graph_ptr& aut);
 
   /// \ingroup emptiness_check_algorithms
   /// \brief Emptiness check of one SCC, for any acceptance condition.
+  ///
+  /// \cite baier.19.atva
   SPOT_API bool
   generic_emptiness_check_for_scc(const scc_info& si, unsigned scc);
 
@@ -46,6 +56,8 @@ namespace spot
   ///
   /// This version makes it possible to ignore the acceptance
   /// condition of the automaton, and use \a forced_acc.
+  ///
+  /// \cite baier.19.atva
   SPOT_API bool
   generic_emptiness_check_for_scc(const scc_info& si, unsigned scc,
                                   const acc_cond& forced_acc);