@article{oai:niigata-u.repo.nii.ac.jp:00001907,
 author = {Tamura, Hiroshi and Nakano, Keisuke and Sengoku, Masakazu},
 issue = {4},
 journal = {IEICE transactions on fundamentals of electronics, communications and computer sciences, IEICE transactions on fundamentals of electronics, communications and computer sciences},
 month = {Apr},
 note = {In this paper we extend the p-collection problem to a flow network with lower bounds, and call the extended problem the lower-bounded p-collection problem. First we discuss the complexity of this problem to show NP-hardness for a network with path structure. Next we present a linear time algorithm for the lower-bounded 1-collection problem in a network with tree structure, and a pseudo-polynomial time algorithm with dynamic programming type for the lower-bounded p-collection problem in a network with tree structure. Using the pseudo-polynomial time algorithm, we show an exponential algorithm, which is efficient in a connected network with few cycles, for the lower-bounded p-collection problem.},
 pages = {651--657},
 title = {The p-Collection Problem in a Flow Network with Lower Bounds},
 volume = {E80-A},
 year = {1997}
}