Function: nfcertify
Section: number_fields
C-Name: nfcertify
Prototype: G
Help: nfcertify(nf): returns a vector of composite integers used to certify
 nf.zk and nf.disc unconditionally (both are correct when the output
 is the empty vector).
Doc: $\var{nf}$ being as output by
 \kbd{nfinit}, checks whether the integer basis is known unconditionally.
 This is in particular useful when the argument to \kbd{nfinit} was of the
 form $[T, \kbd{listP}]$, specifying a finite list of primes when
 $p$-maximality had to be proven, or a list of coprime integers to which
 Buchmann-Lenstra algorithm was to be applied.

 The function returns a vector of coprime composite integers. If this vector
 is empty, then \kbd{nf.zk} and \kbd{nf.disc} are correct. Otherwise, the
 result is dubious. In order to obtain a certified result, one must completely
 factor each of the given integers, then \kbd{addprime} each of their prime
 factors, then check whether \kbd{nfdisc(nf.pol)} is equal to \kbd{nf.disc}.
