Learning optimization models in the presence of unknown relations

In a sequential auction with multiple bidding agents, it is highly challenging to determine the ordering of the items to sell in order to maximize the revenue due to the fact that the autonomy and private information of the agents heavily influence the outcome of the auction. The main contribution of this paper is two-fold. First, we demonstrate how to apply machine learning techniques to solve the optimal ordering problem in sequential auctions. We learn regression models from historical auctions, which are subsequently used to predict the expected value of orderings for new auctions. Given the learned models, we propose two types of optimization methods: a black-box best-first search approach, and a novel white-box approach that maps learned models to integer linear programs (ILP) which can then be solved by any ILP-solver. Although the studied auction design problem is hard, our proposed optimization methods obtain good orderings with high revenues. Our second main contribution is the insight that the internal structure of regression models can be efficiently evaluated inside an ILP solver for optimization purposes. To this end, we provide efficient encodings of regression trees and linear regression models as ILP constraints. This new way of using learned models for optimization is promising. As the experimental results show, it significantly outperforms the black-box best-first search in nearly all settings.Comment: 37 pages. Working pape

Fair task allocation in transportation

Task allocation problems have traditionally focused on cost optimization. However, more and more attention is being given to cases in which cost should not always be the sole or major consideration. In this paper we study a fair task allocation problem in transportation where an optimal allocation not only has low cost but more importantly, it distributes tasks as even as possible among heterogeneous participants who have different capacities and costs to execute tasks. To tackle this fair minimum cost allocation problem we analyze and solve it in two parts using two novel polynomial-time algorithms. We show that despite the new fairness criterion, the proposed algorithms can solve the fair minimum cost allocation problem optimally in polynomial time. In addition, we conduct an extensive set of experiments to investigate the trade-off between cost minimization and fairness. Our experimental results demonstrate the benefit of factoring fairness into task allocation. Among the majority of test instances, fairness comes with a very small price in terms of cost

Aesthetic Beauty in the 18th Century Chinese Novel Guwanyan (Preposterous Words)

This paper explores the tension between the radical sexual description and orthodox rhetoric in 18th century Chinese vernacular narrative. My research focuses on a xiaoshuo fiction, Guwangyan (Preposterous Words), authored by Cao Qujing and composed in 1730. This novel pictures the domestic lives of four families in Nanjing from the end of the 17th century to the early 18th century, including many explicit sexual descriptions. I argue that the author projects the ethic concern through the structure and characterization, while presents the anxiety towards desire in graphic sexual descriptions in the novel. The contrast and complementarity of the structural frame and content make Guwangyan as an important text to study in order to analyze and understand the changing meaning and uses of sexual explicit material in Chinese novels. My argument includes three parts: first, I will introduce the literati’s reading and response to erotic novels in the morally conservative Chinese society of the 18th century. Second, I will demonstrate how the novel is systematically structured by karmic retribution, sexual competition and yin-yang numerology. Third, I suggest that the author of Guwangyan adopts yin-yang fluidity idea to manipulate the characterization, balancing the portrayal of the lewd women, libertines, female heroes and chaste men in the whole narrative. I conclude that although this novel includes several graphic descriptions of sexuality, through yin-yang metaphysics the author always attempts to contain the representation of lust and desire without at the same time disrupting both the self and the social order

Assessment of a marine polysaccharide for use as excipient in pharmaceutical hot-melt extrusion

Pharmaceutical Hot Melt Extrusion (HME) is currently investigated by both industry and academia as a method for manufacturing solid oral dosages with improved bioavailability of poorly-water soluble active pharmaceutical ingredients (APIs) and control drug release of water-soluble APIs. Although HME is traditionally utilizing synthetic polymers to produce such dosages, biopolymers constantly gain ground by virtue of renewability, biocompatibility and in some cases biodegradability. In this work, the possibility of using Keltone, a marine polysaccharide derived from brown seaweed, as a polymeric excipient for pharmaceutical HME is explored. Keltone is insoluble in acidic pH and soluble in basic pH, therefore making it suitable for intestinal drug release. The processability of Keltone by extrusion using water and Eudragit EPO as plasticizers, and Diphenhydramine Hydrochloride and Clotrimazoleas as active pharmaceutical ingredients is assessed. The amount of residual water in the extrudates is determined by thermogravimetric analysis. The thermal transitions of the extrudates are determined by Differential Scanning Calorimetry