  Many cognitive systems deploy multiple, closed, individually consistent
models which can represent interpretations of the present state of the world,
moments in the past, possible futures or alternate versions of reality. While
they appear under different names, these structures can be grouped under the
general term of worlds. The Xapagy architecture is a story-oriented cognitive
system which relies exclusively on the autobiographical memory implemented as a
raw collection of events organized into world-type structures called {\em
scenes}. The system performs reasoning by shadowing current events with events
from the autobiography. The shadows are then extrapolated into headless shadows
corresponding to predictions, hidden events or inferred relations.
