
Pseudorandom generators for polynomials
    
    Encyclopedia
    
        In theoretical computer science
a pseudorandom generator for low-degree polynomials is an efficiently computable function whose output is indistinguishable from the uniform distribution by evaluation of low-degree polynomials in the following sense.
 for polynomials of degree
 for polynomials of degree  over a Finite field
 over a Finite field
F is an efficient procedure that stretches field elements into
 field elements into  field elements and fools any
 field elements and fools any
polynomial of degree d in n variables over F: For every such polynomial p, the statistical distance between the distributions , for uniform
, for uniform  in
 in  , and
, and  , for uniform
, for uniform  in
 in  , is at most a small
, is at most a small  .
.
which give constructions with seed length (this is optimal up to constant factors). Following the sequence of papers (http://www.ccs.neu.edu/home/viola/papers/gen.pdf, http://shachar.lovett.googlepages.com/prg_poly.pdf) it was established in http://www.ccs.neu.edu/home/viola/papers/d.pdf that a sum of
 (this is optimal up to constant factors). Following the sequence of papers (http://www.ccs.neu.edu/home/viola/papers/gen.pdf, http://shachar.lovett.googlepages.com/prg_poly.pdf) it was established in http://www.ccs.neu.edu/home/viola/papers/d.pdf that a sum of  small-bias spaces fools degree
 small-bias spaces fools degree  polynomials. This gives a construction with seed length
 polynomials. This gives a construction with seed length  .
.
        
    
Theoretical computer science
Theoretical computer science  is a division or subset of general computer science and mathematics which focuses on more abstract or mathematical aspects of computing....
a pseudorandom generator for low-degree polynomials is an efficiently computable function whose output is indistinguishable from the uniform distribution by evaluation of low-degree polynomials in the following sense.
Definition
A pseudorandom generator for polynomials of degree
 for polynomials of degree  over a Finite field
 over a Finite fieldFinite field
In abstract algebra, a finite field or Galois field  is a field that contains a finite number of elements. Finite fields are important in number theory, algebraic geometry, Galois theory, cryptography, and coding theory...
F is an efficient procedure that stretches
 field elements into
 field elements into  field elements and fools any
 field elements and fools anypolynomial of degree d in n variables over F: For every such polynomial p, the statistical distance between the distributions
 , for uniform
, for uniform  in
 in  , and
, and  , for uniform
, for uniform  in
 in  , is at most a small
, is at most a small  .
.Construction
The case of linear polynomials is solved by small-bias spacesEpsilon-Biased Sample Spaces
In computer science \epsilon-biased sample spaces, also known as \epsilon-biased generators or small-bias probability spaces, refer to small probability spaces that approximate larger spaces as defined below...
which give constructions with seed length
 (this is optimal up to constant factors). Following the sequence of papers (http://www.ccs.neu.edu/home/viola/papers/gen.pdf, http://shachar.lovett.googlepages.com/prg_poly.pdf) it was established in http://www.ccs.neu.edu/home/viola/papers/d.pdf that a sum of
 (this is optimal up to constant factors). Following the sequence of papers (http://www.ccs.neu.edu/home/viola/papers/gen.pdf, http://shachar.lovett.googlepages.com/prg_poly.pdf) it was established in http://www.ccs.neu.edu/home/viola/papers/d.pdf that a sum of  small-bias spaces fools degree
 small-bias spaces fools degree  polynomials. This gives a construction with seed length
 polynomials. This gives a construction with seed length  .
.
        
    

