A Two-Stage Constrained Submodular Maximization

Author(s):  
Ruiqi Yang ◽  
Shuyang Gu ◽  
Chuangen Gao ◽  
Weili Wu ◽  
Hua Wang ◽  
...  
Author(s):  
Zhicheng Liu ◽  
Hong Chang ◽  
Ran Ma ◽  
Donglei Du ◽  
Xiaoyan Zhang

Abstract We consider a two-stage submodular maximization problem subject to a cardinality constraint and k matroid constraints, where the objective function is the expected difference of a nonnegative monotone submodular function and a nonnegative monotone modular function. We give two bi-factor approximation algorithms for this problem. The first is a deterministic $\left( {{1 \over {k + 1}}\left( {1 - {1 \over {{e^{k + 1}}}}} \right),1} \right)$ -approximation algorithm, and the second is a randomized $\left( {{1 \over {k + 1}}\left( {1 - {1 \over {{e^{k + 1}}}}} \right) - \varepsilon ,1} \right)$ -approximation algorithm with improved time efficiency.


2021 ◽  
Vol 853 ◽  
pp. 57-64
Author(s):  
Ruiqi Yang ◽  
Shuyang Gu ◽  
Chuangen Gao ◽  
Weili Wu ◽  
Hua Wang ◽  
...  

Author(s):  
Yanzhi Li ◽  
Zhicheng Liu ◽  
Chuchu Xu ◽  
Ping Li ◽  
Hong Chang ◽  
...  

Author(s):  
Sengshiu Chung ◽  
Peggy Cebe

We are studying the crystallization and annealing behavior of high performance polymers, like poly(p-pheny1ene sulfide) PPS, and poly-(etheretherketone), PEEK. Our purpose is to determine whether PPS, which is similar in many ways to PEEK, undergoes reorganization during annealing. In an effort to address the issue of reorganization, we are studying solution grown single crystals of PPS as model materials.Observation of solution grown PPS crystals has been reported. Even from dilute solution, embrionic spherulites and aggregates were formed. We observe that these morphologies result when solutions containing uncrystallized polymer are cooled. To obtain samples of uniform single crystals, we have used two-stage self seeding and solution replacement techniques.


2007 ◽  
Vol 177 (4S) ◽  
pp. 121-121
Author(s):  
Antonio Dessanti ◽  
Diego Falchetti ◽  
Marco Iannuccelli ◽  
Susanna Milianti ◽  
Gian P. Strusi ◽  
...  
Keyword(s):  

2007 ◽  
Vol 177 (4S) ◽  
pp. 120-120
Author(s):  
Pamela I. Ellsworth ◽  
Anthony Caldamone
Keyword(s):  

2005 ◽  
Vol 38 (18) ◽  
pp. 68
Author(s):  
SHARON WORCESTER
Keyword(s):  

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