The subset consisting of all elements of a given set is called an improper subset (Kamke 1950, p. 6).
Improper Subset
See also
Proper Subset, Set, SubsetExplore with Wolfram|Alpha
References
Kamke, E. Theory of Sets. New York: Dover, 1950.Referenced on Wolfram|Alpha
Improper SubsetCite this as:
Weisstein, Eric W. "Improper Subset." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/ImproperSubset.html