Subset
A portion of a Set. 
is a subset of 
(written 
) Iff every member of is a member of. If is a Proper Subset of (i.e., a subset other than the set itself), this is written 
.
A Set of 
elements has 
subsets (including the set itself and the Empty Set). For sets of 
, 2,... elements, the numbers of subsets are therefore 2, 4, 8, 16, 32, 64, ... (Sloane's A000079). For example,the set 
has the two subsets 
and . Similarly, the set 
has subsets (the Empty Set, , 
, and .
References
Courant, R. and Robbins, H. What is Mathematics?: An Elementary Approach to Ideas and Methods, 2nd ed. Oxford, England: Oxford University Press, p. 109, 1996. Ruskey, F. ``Information of Subsets of a Set.'' http://sue.csc.uvic.ca/~cos/inf/comb/SubsetInfo.html. Sloane, N. J. A. SequenceA000079/M1129in ``An On-Line Version of the Encyclopedia of Integer Sequences.''http://www.research.att.com/~njas/sequences/eisonline.html and Sloane, N. J. A. and Plouffe, S.The Encyclopedia of Integer Sequences. San Diego: Academic Press, 1995.
- Polar
- Polar Angle
- Polar Circle
- Polar Coordinates
- Polarity
- Polar Line
- Pole
- Pole (Geometry)
- Pole (Origin)
- Policeman on Point Duty Curve
- Polignac's Conjecture
- Polish Space
- Pollaczek Polynomial
- Pollard Monte Carlo Factorization Method
- Pollard p-1 Factorization Method
- Pollard Rho Factorization Method
- Poloidal Field
- Polyabolo
- Polyconic Projection
- Polycube
- Polydisk
- Polygamma Function
- Polygenic Function
- Polygon
- Polygonal Knot