Context-Aware Computing

Table 3.9: Probabilistic Customer and CustomerLoc relations.

(a) Probabilistic Customer relation (tuple-level uncertainty)

(b) Probabilistic CustomerLoc relation (attribute-level uncertainty), where N(μ, 𝜎2) is normal distribution with probabilistic density function $f\left(\text{x}\right)=\frac{1}{\sqrt{2\pi \sigma }}{e}^{-\frac{{\left(x-\mu \right)}^2}{2{\sigma }^2}},$ μ is mean and 𝜎2 is variance.

ID	CName	Location
l1	Lily	N(2, 1)
l2	Tom	N(5, 1)
l3	Jessica	N(3, 1)

The probability of each possible world can be computed by multiplying its tuples’ probabilities.

Besides tuple-wise uncertainty, attribute-level uncertainty (e.g., Location attribute in the CustomerLoc relation in Table 3.9(b)) ...