• The Inria's Research Teams produce an annual Activity Report presenting their activities and their results of the year. These reports include the team members, the scientific program, the software developed by the team and the new results of the year. The report also describes the grants, contracts and the activities of dissemination and teaching. Finally, the report gives the list of publications of the year.

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## Section: New Results

### Drags

Shared and cyclic structures are very common in both programming and proving, which requires generalizing term rewriting techniques to graphs. Jean-Pierre Jouannaud and Nachum Dershowitz have introduced a very general class of multigraphs, called drags, equipped with a composition operator $\otimes$ which provides with a rich categorical structure. Rewriting a drag $D$ can then be defined in a very simple way, by writing $D$ as the composition of a left-hand side of rules $L$ and a context $C$, and then replacing $L$ by $R$, the right-hand side of the rule, which yields the rewritten drag $R\otimes C$. The fundamental aspects of the algebra of drags have been presented at TERMGRAPH'2018 and have also been submitted to a special issue of TCS. Termination of drag rewriting in investigated in [20].