We would like to make the following paper announcement. Title: Constructing free Boolean Categories Authors: Francois Lamache and Lutz Strassburber This is an expanded version of our LICS’05 submission. Mistakes have been corrected and the relative emphasis of axioms has changed, but the claims are strictly identical. Abstract: By Boolean category we mean something which is to a Boolean algebra what a category is to a poset. We propose an axiomatic system for Boolean categories, which differs in several respects from the one given very recently by Fuehrmann and Pym. In particular everything is done from the start in a *-autonomous category and not a linear distributive one, which simplifies issues like the Mix rule. An important axiom, which is introduced later, is a ``graphical'' condition, which is closely related to denotational semantics and the Geometry of Interaction. Then we show that the proof net model we presented in TLCA2005 is the free ``graphical'' Boolean category in our sense. This validates our categorical axiomatization with respect to a real-life example. Another important aspect of this work is that we do not assume a-priori the existence of units in the *-autonomous categories we use. This has some retroactive interest for the semantics of linear logic, and is motivated by the properties of our TLCA proof nets with respect to units. This paper (as well as its predecessors) is available on the following pages: http://www.ps.uni-sb.de/~lutz/ http://www.loria.fr/~lamarche/ François Lamarche and Lutz Strassburger 21-Feb-2005 15:45:38 -0400,1215;000000000000-00000000