 There are also other viable logical perspectives. In particular, one can look at game theory the way mathematical logicians look at any branch of mathematics. Following the style of the famous Erlangen Program, one can discuss the structures studied in that field and look for structural invariance relations and matching logical languages. Game theory is rich in structure, as it has several different natural notions of invariance. The tree format of extensive games offers a detailed view of what happens step by step as players make their moves, whereas the matrix format of strategic form games offers a high-level view that centers on outcomes. Yet other formats, to be discussed below, focus on players’ control over the various outcomes. All these different levels of game structure come with their own logical systems, as will be detailed in  Section 2.  Moreover, these different logics do not just provide isolated snapshots: they can be related in a systematic manner.