 Here, the Proponent’s moves at steps (3.\(i\)) answer the question asked by Opponent at step (1), not the questions asked by the Opponent at steps (3.1), (3.2) that are still pending. This violates a “no dangling question mark” condition on dialogues introduced under this name by Robin Gandy in his unpublished work on higher-type computability (and well-known in the tradition of game semantics for intuitionistic logic initiated by Lorenzen (1961)). Strategies such as these interpret control operators that do not exist in the fully abstract game model of PCF, but do exist, for example, in the model based on sequential algorithms (Curien 1986: sec. 3.2.7, 3.2.8). A different phenomenon occurs in a variation of the previous example: