Solution
= Solution
Integrate the type-A first-event density from zero to $t$. \b[The type-A cumulative incidence is]
$$
\boxed{F_A(t)=\Pr(T\leq t,J=A)
=\int_0^t\alpha e^{-(\alpha+\beta)u}du
=\frac\alpha{\alpha+\beta}(1-e^{-(\alpha+\beta)t}).}
$$
This is the <cumulative incidence function> in the <competing risks model>, distinct from the hypothetical net risk $1-e^{-\alpha t}$ obtained by removing B.