Introducing Floating Singletons with an example application in clinic spirometry

Fuzzy-logic models where singletons are placed in the consequents of rules of the type if x is Ai and y is Bj then zi = si are used nowadays in many soft computing applications. In this work we introduce the concept of floating singletons where their precise location on the real axis is only known at run-time. At design time some intervals are established where this special singletons are allowed to float and later, the defuzzification of a complementary fuzzy model fixes their location. As an example, a complete model for detecting Chronic Obstructive Pulmonary Disease is introduced, taking into account values from spirometric tests and the effects of smoking in patients.