After a long spell of frigid days, we may call a milder but still chilly day relatively warm. Human reasoning filters and interprets information in order to arrive at conclusions or to dismiss it as inconclusive. Although machines cannot yet handle imprecise information in the same ways that humans do, computer programs with fuzzy logic are becoming quite useful when the sheer volume of tasks defies human analysis and action. An organized method for dealing with imprecise data is called fuzzy logic . The data are considered as fuzzy sets .
Fuzzy sets allow partial membership.
A ten-year old considers smaller children young. On the other hand, people in the geriatric group may consider those under 70 as young and someone over 90 as old. For example, we might be setting up a screening procedure in which age is a criterion. Although fuzzy logic avoids sharp decisions, there is no reason to make the criteria so broad that classification is illogical. You could argue about 15 or 40 as the cut offs, but a good or bad fuzzy decision depends on whether it suits a particular problem.