Closed World Assumption

Open versus Closed world assumption. The openness of the Web, described by the AAA Slogan, has additional implications on Semantic Web applications beyond the Nonunique Naming Assumption discussed in Sect. 3.4.1. With respect to reasoning, Semantic Web systems are built on the assumption that the system has incomplete information and therefore adopt an Open World Assumption (OWA). Under the OWA, information that is not explicitly stated is considered unknown rather than false. For example, asking whether mo Engl has Ford as a supplier, will not return No, but an empty value set. By contrast, database systems operate under a Closed World Assumption (CWA) and therefore assume complete information. In other words, information that is not known is considered false. The same query as above will return No as a result under CWA. 

Rawls criticism is close to a point made repeatedly by Arendt. The members of a political community do not have a single interest and one opinion. Rather, they are a plurality of individuals, all alike in that they are members of the same species, but different in their perspective on the world and in their opinions. The domination of one interest and one opinion, and the assumption that it is shared by everyone, is in effect equivalent to one-person rule — it is a form of tyranny (Arendt, 1958, p40). 

Canada has about 36 per cent of the world peat area, and at least 50 per cent of the lake surfaces within the Boreal and Arctic biomes. If the figures of Table I are weighted with these areas, on the assumption that conditions have been similar in Eurasia it can be estimated that world post-glacial carbon accumulation in high latitude bogs, peats, soils and lakes may have been close to 500 Gt, equivalent to 70 per cent of present atmospheric storage. Present annual rates of withdrawal may be close to 80 X 10 t a ( 0.1 Gt per annum). 

It is remarkable that with relatively modest theoretical tools we have been able to account for the problem of thennal relaxation from a microscopic approach. Still, one should keep in mind the approximations made above when trying to relate these results to the real world. Our main assumption (made in the paragraph above Eq. (9.54)) was that C((w) is finite and fairly constant in a sizable neighborhood about (Wo- In particular, we have assumed that y is much smaller than the extent of this neighborhood. C((w) in turn is dominated by the mode density g(. Our theory will fail if cwq is very close to 0 or to a sharp feature in g((w). 

In the first place the reference to the concept of stuff is a macroscopic view, a view very close to or rooted in the manifest world. There are early attempts to describe chemical substances and their changes without reference to a particle picture but in an empiricist or operationalist attitude. Wilhelm Ostwald (1853-1932) was among those who were skeptical of metaphysical assumptions in general and with speculative atomism in particular. He claimed that a recognized chemical substance must be capable of being isolated as a stuff sample. In his book on electrochemistry from 1896 he wrote ... 

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