Abstract
For nonsingular projective 4-folds V of general type with plurigenus for some positive integer m0, we show that is birational onto its image for all integers and the canonical volume has the lower bound . This improves earlier results of Meng Chen.
Acknowledgments
The author would like to express great gratitude to Professor Meng Chen for his suggestion of this problem and his guidance over this paper. The author is also obliged to Yong Hu for the enlightening discussions of the problem and his help in making the paper much more readable. The author would also like to thank the referee for valuable suggestions and comments.