Reading Group

As of January 1, 2015, this reading group is in hiatus.

The Reading Group on Fixed Points meets once every two weeks to discuss the intersection of fixed points and proof theory. The discussion format is explained below.


  1. Classes of recursive functions: the Grzegorczyk hierarchy
  2. Paco: A Coq Library for Parameterized Coinduction
  3. Recursion from Iteration
    • Tuesday, April 8, at 14:00 in the Salle Schützenberger
    • Main paper: Andrzej Filinski, “Recursion from Iteration“, LISP and Symbolic Computation, 1994
    • Pen: D. Ilik
  4. FO+LO+LFP=PTIME and related results in Descriptive Complexity Theory
  5. Least and Greatest Fixed Points in MALL (Sequent Calculus)

Reading Stack

These papers/topics have been suggested for the reading group and may be part of future meetings.

  • Work on cyclic structures and traced monoidal categories. Examples:
    • Masahito Hasegawa, “Recursion from Cyclic Sharing: Traced Monoidal Categories and Models of Cyclic Lambda Calculi”, TLCA 1997
    • —, “On traced monoidal categories”, MSCS 2009


  • Every participant is expected to have read the main assigned paper(s) and to have a list of prepared “questions” before the meeting. A meeting will be convened only when there is “quorum”, meaning that more than floor(half the group) have indicated that they have read the main papers and wish to discuss them.
  • A “question” can be about, but is not limited to, the assigned papers, the subject of the assigned papers, or relationships to other subjects or papers. “Questions” need not end with a question mark, but they should not be used to soapbox, nor to incite meandering discussions that do not increase the general comprehension of the assigned papers.
  • Every group is led by a Holder of The Pen whose task at the start of the meeting is to gather and arrange all the “questions” on the board in a sensible order. The Holder is not expected to be an expert, merely to direct the meeting and most importantly to bring it to an end in a reasonable amount of time (1 to 1.5 hours).
  • The last person to arrive at a meeting is required to ask the first “question”.
  • Not every “question” needs to be answered in the meeting.
  • Each meeting will end with the selection of the following session’s assigned papers. A Holder will be selected from volunteers, or based on an LRU algorithm.