*Definition [#r5355ed0]
-For two [[soft sets>soft set]] (F , A) and (G , B) over a common universe U, we say that (F , A) is a soft subset of (G , B) if A ⊆ B and for all e ∈ A, F (e) and G(e) are identical approximations.
We write &ref(http://www.eaflux.com/imgtex/imgtex.fcgi?%5bres=100%5d%7b%5c%5b%20%28F%2cA%29%5cwidetilde%7b%5csubset%7d%28G%2cB%29%20%5c%5d%7d%25.png);.

*Reference [#ofa65ca5]
-Maji P. K.,  Biswas R.,  Roy A. R., ''Soft set theory.'' (English summary), Comput. Math. Appl. 45 (2003), no. 4-5, 555-562.