Félicitations, André Jacob!

Jacob " Evolution and Tinkering " ( 1977 ) , by Francois Jacob

In his essay "Evolution and Tinkering," published in Science in 1977, François Jacob argues that a common analogy between the process of evolution [4] by natural selection [5] and the methods of engineering is problematic. Instead, he proposes to describe the process of evolution [4] with the concept of bricolage (tinkering). In this essay, Jacob does not deny the importance of the mechanism of...

A conjecture of Yves André . ∗

The introduction to [2] (and references contained therein) contains a comprehensive exposition of terminology and notations relative to this conjecture. Since we use the same terminology and notations, we do not reproduce them here. The introduction to [2] also contains an exposition of results on this conjecture obtained before the article [3] came out. In this article we prove the following t...

Jacob Ross

How is what an agent ought to do related to what an agent ought to prefer that she does? More precisely, suppose we know what an agent’s preference ordering ought to be over the outcomes of performing the various courses of action open to her. Can we infer from this information how she ought to act, and if so, how can we infer it? One view (which, for convenience, I will call ‘actualism’) is th...

François Bach and André Herbelin

Reals which Compute Little André

We investigate combinatorial lowness properties of sets of natural numbers (reals). The real A is super-low if A′ ≤tt ∅′, and A is jump-traceable if the values of {e}A(e) can be effectively approximated in a sense to be specified. We investigate those properties, in particular showing that super-lowness and jump-traceability coincide within the r.e. sets but none of the properties implies the o...