Pythagorean Membership Grades in Multicriteria Decision Making

TLDR

Nonstandard fuzzy sets such as intuitionistic and interval‑valued sets, and the need to compare Pythagorean membership grades in multicriteria decision making, motivate this study. The study aims to apply Pythagorean membership grades to multicriteria decision making. The authors formulate the negation and complement operations for these sets, define a Pythagorean complement, introduce nonstandard Pythagorean fuzzy subsets with grades (a,b) satisfying a²+b²≤1, and develop aggregation operations for use in MCDM. They demonstrate that these sets allow a degree of commitment less than one and provide a new class of Pythagorean fuzzy subsets with corresponding aggregation operations.

Abstract

We first look at some nonstandard fuzzy sets, intuitionistic, and interval-valued fuzzy sets. We note both these allow a degree of commitment of less then one in assigning membership. We look at the formulation of the negation for these sets and show its expression in terms of the standard complement with respect to the degree of commitment. We then consider the complement operation.We describe its properties and look at alternative definitions of complement operations.We then focus on the Pythagorean complement. Using this complement, we introduce a class of nonstandard Pythagorean fuzzy subsetswhose membership grades are pairs, (a, b) satisfying the requirement a2 + b2 ≤1.We introduce a variety of aggregation operations for these Pythagorean fuzzy subsets. We then look at multicriteria decision making in the case where the criteria satisfaction are expressed using Pythagorean membership grades. The issue of having to choose a best alternative in multicriteria decision making leads us to consider the problem of comparing Pythagorean membership grades.