A soft set FA on the universe U is defined by the set of ordered pairs FA = {(x, fA (x)): x ∈ E, fA (x) ∈ P (U)}, where fA : E → P (U ) such that fA (x) = ∅ if x A. Here fA is called an approximate function of the soft set FA. The value of fA may be arbitrary, some of them may be empty, and some may have non empty intersection.

Suppose there are five cars in the universe .Let U = {c1,c2,c3,c4,c5} under consideration and that E={x1,x2,x3,x4,x5,x6,x7,x8} stand for the parameters expensive, beautiful, manual gear, cheap, automatic gear, in good repair, in bad repair and costly respectively. In this case to define a soft set means to point out expensive cars, beautiful cars and so on. It means that in the mapping fA given by “cars,(.)” where (.) to be filled in by one of the given parameters xi ∈ E.

Let A ⊆E , the soft set FA that describes the “ attractiveness in cars” in the opinion of a buyer may be defined like A={x2,x3,x4,x5,x7} , fA(x2)={c2,c3,c5} fA(x3)={c2,c4} fA(x4)={c1}, fA(x5)={U} fA(x7)={c3,c5}.Then collection of the above approximations is called as soft set F A={ (x2,{c2,c3,c5}) (x3,{c2,c4}),(x4,{c1}), (x5,{U}) (x7,{c3,c5})}

can we take soft set with one parameter as crisp set?