After picking in the literature a selected panel of solving strategies, we will formalize several levels in a structured search: * Global search with both a strategic level and an exploration level, * Local search with one or multiple schemes * Meta Level strategy We will derive some classic patterns from these different notions and suggest a more general framework based on keyword patterns. It will be possible in the first place to express most of the existing strategies and in the second place to build (manually or automatically) new ones.