Groups and monoids

• An effective version of Stallings' theorem in the case of context-free groups.
  (In proceedings ICALP'93).
  

• On the finite subgroups of a context-free group.
  (In DIMACS series in Discrete Maths and Theoretical Computer Science, vol. 25,1996)
• Semi-groups acting on context-free graphs.
  (LaBRI internal report nr 1094-95; short version in proceedings ICALP'96)
• Equations in free inverse monoids.
  (In IJAC; with T. Deis and J. Meakin)
  talk (.pdf)
• When is a Graph Product of Groups virtually free ?
  (In Communications in Algebra; with M. Lohrey)
• Rational subsets of HNN extensions.
  (with M. Lohrey; in IJAC; short version in proceedings ICALP'06, LNCS 4052, p. 504-515)
  talk (.pdf)
• Equations in HNN extensions.
  (Manuscript; with M. Lohrey; short version in proceedings ICALP'06)
  talk (.pdf)
• Positive theories of HNN extensions and amalgamated free products.
  (Manuscript; with M. Lohrey; short version in proceedings ICALP'06)
• Higher-order pushdowns and monoids .
  talk (.pdf)
  (Advanced seminar given at SATA'08, Lisbon)