so let us focus on the preference based approach and let's define three preference relations there are all binary relations so the consumer is engaging in a series of pairwise comparisons and every time the consumer is comparing between two alternatives x and y so these binary relations are all defined on X and X is the set of possible and mutually exclusive alternatives from which the individual must choose so the starting point is the weak preference relation we say that X is at least as good as Y or weakly preferred to Y and we can use this
as a starting point to derive to other preference relations the strict preference relation we say that X is strictly preferred to Y if and only if X is at least as good as Y but Y is not at least as good as X and then the indifference relation we say that we are indifferent between x and y if and only if we have both x is at least as good as Y and Y is at least as good as X