  Trustworthiness especially for service oriented system is very important
topic now a day in IT field of the whole world. Certain Trust Model depends on
some certain values given by experts and developers. Here, main parameters for
calculating trust are certainty and average rating. In this paper we have
proposed an Extension of Certain Trust Model, mainly the representation portion
based on probabilistic logic and fuzzy logic. This extended model can be
applied in a system like cloud computing, internet, website, e-commerce, etc.
to ensure trustworthiness of these platforms. The model uses the concept of
fuzzy logic to add fuzziness with certainty and average rating to calculate the
trustworthiness of a system more accurately. We have proposed two new
parameters - trust T and behavioral probability P, which will help both the
users and the developers of the system to understand its present condition
easily. The linguistic variables are defined for both T and P and then these
variables are implemented in our laboratory to verify the proposed trust model.
We represent the trustworthiness of test system for two cases of evidence value
using Fuzzy Associative Memory (FAM). We use inference rules and
defuzzification method for verifying the model.
