Solution
= Solution
The <survivor function> of a nonnegative event time is
$$
\boxed{F(t)=\mathbb P(T>t)=\int_t^\infty f_T(u)\,du.}
$$
Here the paper uses $F$ for the <survival function>, rather than for the <cumulative distribution function>; the latter is $1-F(t)$ for a continuous distribution. The <survivor function> is nonincreasing, starts at 1 when there is no atom at zero, and tends to zero for an almost surely finite event time.