|f(x)| <= C|g(x)| whenever x > k
"f is big oh of g"
the constants C and k in the definition of bigO notation are called witnesses to the relationship f is O(g). To establish that f is O(g) we need only one pair of witnesses to this relationship
. ... Note that when there are one pair of witnesses to the relationship f is O(g), there are infinitely many pairs of witnesses.
To see this, note that if C and k are one pair of witnesses, then any pair C' and k' where C < C' and k < k', is also a pair of witnesses, since
|f(x)| <= C|g(x)| = C'g(x) whenever x > k' > k.