Dear members of the mailing list, I'm pleased to annouce that the paper ``Rewriting on Cyclic Structures'', by myself and Andrea Corradini, is available at http://www.di.unipi.it/~gadducci/papers/RAIRO.ps. The abstract follows, but shortly, it uses traced monoidal 2-categories --where, in addition, each object ha`s a comonoidal structure-- in order to simulate various kinds of (eventually cyclic) term (graph) rewriting. Its interest for a broader audience may lie, besides in showing a practical application of the trace structure in the rewriting field, in its appendix, where we tried to sketch a very SHORT history of the notion of feedback in theoretical computer science, with a particular attention to the algebraic specification field. We found it interesting to review previous approaches to the topic, after the results of Joyal-Street-Verity have newly sparkled the interest in the algebraic description of fixed points (see e.g. the recent paper by Selinger advertised a few weeks ago on this mailing list). Best regards, Fabio Gadducci xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx \begin{abstract} We present a categorical formulation of the rewriting of possibly cyclic term graphs, based on a variation of algebraic 2-theories. We show that this presentation is equivalent to the well-accepted operational definition proposed by Barendregt et alii---but for the case of ``circular redexes'', for which we propose (and justify formally) a different treatment. The categorical framework allows us to model in a concise way also automatic garbage collection and rules for sharing/unsharing and folding/unfolding of structures, and to relate term graph rewriting to other rewriting formalisms. \end{abstract}