Abstract:
The semiampleness of the divisor $-(K_X+S)$ is proved for a pair $(X,S)$
with purely log terminal $\mathbb Q$-factorial singularities, where $X$
is a three-dimensional normal projective algebraic variety and $S\subset X$
is a normal surface such that the divisor $-(K_X+S)$ is nef and big.
Bibliography: 8 titles.