Co-operation of any complexity depends on successful communication. This in turn requires both a common coding/ decoding system, and matching schemas. How well two invisible objects match is necessarily a matter of some uncertainty, whatever they may be; and this uncertainty applies with particular force to concepts (tanggapan-tanggapan) and schemas (gagasan-gagasan). Where these are of a fairly low order of abstraction, a shared environment (suatu sekitaran kongsian) makes the assumption of matching schemas not too unreasonable. Where high-order abstractions are concerned, it is a different matter.