Designing Fuzzy Model. i,k The client’s level of greediness βc can be increased or decreased depending on the resource availability in the Grid. According to the intuition of Xxxxxxxxx and Xxx- xxxxx [112], if the resource availability decreases, the client has to become more gen- erous to reach an agreement with the GRA before the resources are exhausted. If the resource availability increases, the client has to become less generous to avoid losing its utility without a risk of resource exhaustion. However, the issue is how to distin- guish between the “large” or “small” increase/decrease of the resource availability in the Grid. The client estimates only the relative change δi,k (see Formula (3.20)) of the i,k GRA’s negotiation interval ΣGmin, GmaxΣ. In other words, the client is not absolutely certain whether a specific value of δi,k denotes a significant or an insignificant change of the GRA’s reservation amount of resource. Therefore, the client evaluates whether the resource availability has changed substantially using a fuzzy representation of δi,k. That is, the client is only able to state with some degree of certainty that the GRA’s reservation amount of resource has decreased or increased significantly. If the change of resources is insignificant than we believe that the client will not benefit from a sig- nificant change of its level of greediness because the client is uncertain whether a risk of resource exhaustion is large or small. The client also has to take into account its current level of greediness to decide how this level can be changed in the current negotiation round. For example, if the client applies generous tactic and the resource availability decreases, the client may not need to become more generous because the client may lose its utility. However, if the client applies greedy tactic and the resource availability decreases, the client has to become more generous because the client may fail negotiation. We believe that the client may significantly change its level of greediness if it applies a greedy or generous tactic but a significant change will not be beneficial if the client applies an indifferent tactic. In this way, we try to find a balance between a risk of negotiation failure and loss of utility. Therefore, the client has to decide with some degree of certainty whether its current tactic is “more” or “less” generous or greedy to change more or less significantly its level of greediness. The output of our fuzzy mechanism shows how the client’...
