401 research outputs found
A note on approximating the minâmax vertex disjoint paths on directed acyclic graphs
AbstractThis paper shows that the FPTAS for the minâmax disjoint paths problem on directed acyclic graphs by Yu et al. (2010) [7] can be improved by a rounding and searching technique
Approximation algorithms for the shortest total path length spanning tree problem
AbstractGiven an undirected graph with a nonnegative weight on each edge, the shortest total path length spanning tree problem is to find a spanning tree of the graph such that the total path length summed over all pairs of the vertices is minimized. In this paper, we present several approximation algorithms for this problem. Our algorithms achieve approximation ratios of 2, 15/8, and 3/2 in time O(n2+f(G)),O(n3), and O(n4) respectively, in which f(G) is the time complexity for computing all-pairs shortest paths of the input graph G and n is the number of vertices of G. Furthermore, we show that the approximation ratio of (4/3+Δ) can be achieved in polynomial time for any constant Δ>0
The maximum disjoint paths problem on multi-relations social networks
Motivated by applications to social network analysis (SNA), we study the
problem of finding the maximum number of disjoint uni-color paths in an
edge-colored graph. We show the NP-hardness and the approximability of the
problem, and both approximation and exact algorithms are proposed. Since short
paths are much more significant in SNA, we also study the length-bounded
version of the problem, in which the lengths of paths are required to be upper
bounded by a fixed integer . It is shown that the problem can be solved in
polynomial time for and is NP-hard for . We also show that the
problem can be approximated with ratio in polynomial time
for any . Particularly, for , we develop an efficient
2-approximation algorithm
Improving Medical Report Generation with Adapter Tuning and Knowledge Enhancement in Vision-Language Foundation Models
Medical report generation demands automatic creation of coherent and precise
descriptions for medical images. However, the scarcity of labelled medical
image-report pairs poses formidable challenges in developing large-scale neural
networks capable of harnessing the potential of artificial intelligence,
exemplified by large language models. This study builds upon the
state-of-the-art vision-language pre-training and fine-tuning approach, BLIP-2,
to customize general large-scale foundation models. Integrating adapter tuning
and a medical knowledge enhancement loss, our model significantly improves
accuracy and coherence. Validation on the dataset of ImageCLEFmedical 2023
demonstrates our model's prowess, achieving the best-averaged results against
several state-of-the-art methods. Significant improvements in ROUGE and CIDEr
underscore our method's efficacy, highlighting promising outcomes for the rapid
medical-domain adaptation of the vision-language foundation models in
addressing challenges posed by data scarcity
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