A multiobjective genetic algorithm for job shop scheduling

In this paper, a Multi Objective Genetic Algorithm (MOGA) is proposed to derive the optimal machine-wise priority dispatching rules ( pdrs ) to resolve the conflict among the contending jobs in the Giffler and Thompson (GT) procedure applied for job shop problems. The performance criterion considered is the weighed sum of the multiple objectives minimization of makespan, minimization of total idle time of machines and minimization of total tardiness. The weights assigned for combining the objectives into a scalar fitness function are not constant. They are specified randomly for each evaluation. This in turn leads to the multidirectional search in the proposed MOGA, which in turn mitigates the solution being entrapped in local minima. The applicability and usefulness of the proposed methodology for the scheduling of job shops is illustrated with 28 benchmark problems available in the open literature.     

Races without Racism?: everyday race relations in Singapore

In Singapore, race has a prominent place in the city state’s national policies. Its political ideology of multiracialism proclaims racial equality and protection for minority groups from racial discrimination. However, despite official rhetoric and policies aimed at managing and integrating the different ethnic groups, some scholars have argued that institutional racism does exist in Singapore. While it is public knowledge, with few exceptions, racist provocations and experiences of racism are not publicly discussed. In recent years, the advent of social media has made it possible for Singaporeans oftentimes unwittingly to express racially derogatory remarks. This has highlighted that racism is much more deep rooted. Yet, it still remains the white elephant in the room. This paper examines the sociopolitical context that has contributed to everyday racial discrimination and calls for a public acknowledgement of racism so as to combat racist practices.     

Street‐level discretion,emotional labour and welfare frontline staff at the Australian employment service providers

Despite the current controversial debates about discretion in public bureaucracies in general, and in welfare agencies in particular, the current literature on street‐level bureaucracy mainly assumes that discretion is a distinctive feature of the daily work of public servants. Nonetheless, a pertinent question has not specifically been asked in this literature, that is, given the context of privatisation and increased welfare conditionality in the welfare sector that are seriously challenging welfare frontline staff's commitment to social justice and human rights‐based practices, what are forms of street‐level discretion likely to contribute to improving the quality of welfare services? In this study, we attempt to address this question by exploring discretion displayed by welfare frontline staff in four Australian employment service providers. We argue that emotional labour, especially when being informed by critical empathy, is an important and effective form of street‐level discretion that welfare frontline workers can perform to better support welfare recipients and minimise the punitive aspects of welfare policy.     

Risk assessment of outsourcing e-procurement services: integrating SWOT analysis with a modified ANP-based fuzzy inference system

With electronic procurement solutions becoming increasingly sophisticated, many firms opt to source these services from third-party providers, effectively transferring (outsourcing) significant responsibility to these services companies. This action, however, entails certain risks, which are oftentimes difficult to assess. To guide managerial practice and to advance academic inquiry in this domain, we identify e-procurement risk factors through a strengths, weaknesses, opportunities, threats analysis, grounded in transaction cost economics (TCE), and propose a risk assessment framework based on the opinions of a group of experts. The approach taken is that of a modified analytic network process methodology, combined with a fuzzy inference system, which is versatile enough to accept the expert opinions in different input formats (such as linguistic variables and ranges). The proposed framework has the capability to aggregate expert judgements’ to estimate risk likelihoods, risk severities and risk factor indices, and derive overall risk magnitudes. The multi-method approach was motivated and is illustrated by a real-life case study of an Indian manufacturing company currently in the process of contract renewal with its existing e-procurement service provider.     

An exact algorithm for the multicriteria ordered clustering problem

In the context of multicriteria decision aid, we address the problem of regrouping alternatives into completely ordered categories based on valued preference degrees. We assume that the number of groups is fixed a priori. This will be referred to as the multicriteria ordered clustering problem. The model is based on the definition of an inconsistency matrix and only uses the ordinal properties of the pairwise preference relations. An exact algorithm is proposed to find the ordered partition and is applied as illustration to the Human Development Index.     

The Impact of Geographic Proximity on What to Buy,How to Buy,and Where to Buy: Evidence from High‐Tech Durable Goods Market*

Social contagion effects due to geographical proximity refer to the social effects wherein the behavior of an individual varies with the behavior of other individuals who are geographically close. Although the influence of such effects on consumer choices has been established in several contexts, much of the extant studies have focused on its effect on consumers’ decision of whether to buy a new product or adopt a new innovation. There has been no systematic examination of the influence of geographic proximity on other aspects of consumers’ product buying process such as what to buy (i.e., brand choice), how to buy (i.e., the channel), and where to buy (i.e., retailers). Such effects can matter significantly in high‐technology and durable goods markets and therefore, it is critical to understand the scope of these on consumers’ choice of retailers and channel as well. Drawing on literatures from word of mouth effects, ecommerce, and consumers’ perception of risk in their purchase process, we develop a set of hypotheses on the effect of geographic proximity on consumers’ choices of what to buy, how to buy, and where to buy. Leveraging a microlevel dataset of purchases of personal computers, we develop brand‐, retailer‐, and channel‐related measures of proximity effects at the individual consumer level and estimate a joint disaggregate model of the three choices that make up a product purchase process to test these hypotheses. Our results indicate a significant contagion effect on each of the three choices. Furthermore, we find evidence of a greater effect of geographic proximity on inexperienced consumers—those who are new to the product category. Our results thus help develop a holistic understanding of the influence of social contagion effects on consumers’ decision making.     

On the Hardness of Approximating the Min-Hack Problem

We show several hardness results for the Minimum Hacking problem, which roughly can be described as the problem of finding the best way to compromise a target node given a few initial compromised nodes in a network. We give several reductions to show that Minimum Hacking is not approximable to within where δ = 1− ^c n, for any c < 1/2. We also analyze some heuristics on this problem.