**3.4. Inference mechanism**

The inference mechanism employed in pH control is based on individual rule firing. In this scheme, contribution of each rule is evaluated and overall decision is derived.

During inference process, each rule that is fired by a crisp value of pH is summed up after giving the weightages decided by the fuzzification unit. This weightage is called degree of satisfaction (DoS). DoS is decided by the fuzzification module.

In the inference mechanism, depending on which all fuzzy sets the input belongs to, the corresponding rules are fired. This describes the functioning of the three out of four blocks in the fuzzy controller. Now comes the defuzzification section.

