Integrating anticipative replenishment-allocation with reactive fulfillment for online retailing using robust optimization

Ministry of Education, Singapore under its Academic Research Funding Tier 1; Lee Kong Chian Fellowship; MPA Research Fellowshi

Epistasis between cultural traits causes paradigm shifts in cultural evolution

Every now and then the cultural paradigm of a society changes. While current models of cultural shifts usually require a major exogenous or endogenous change, we propose that the mechanism underlying many paradigm shifts may just be an emergent feature of the inherent congruence among different cultural traits. We implement this idea through a population dynamics model in which individuals are defined by a vector of cultural traits that changes mainly through cultural contagion, biased by a 'cultural fitness' landscape, between contemporary individuals. Cultural traits reinforce or hinder each other (through a form of cultural epistasis) to prevent cognitive dissonance. Our main result is that abrupt paradigm shifts occur, in response to weak changes in the landscape, only in the presence of epistasis between cultural traits, and regardless of whether horizontal transmission is biased by homophily. A relevant consequence of this dynamics is the irreversible nature of paradigm shifts: the old paradigm cannot be restored even if the external changes are undone. Our model puts the phenomenon of paradigm shifts in cultural evolution in the same category as catastrophic shifts in ecology or phase transitions in physics, where minute causes lead to major collective changes.This work was supported by the Spanish projects VARIANCE (FIS2015-64349-P, MINECO/FEDER, UE), BASIC (FIS2018-098186-B-100, MICINN/FEDER, UE), MiMevo (FIS2017-89773-P, MINECO/FEDER, UE) and SEV-2013-0347 (MINECO).Publicad

Text Similarity Between Concepts Extracted from Source Code and Documentation

Context: Constant evolution in software systems often results in its documentation losing sync with the content of the source code. The traceability research field has often helped in the past with the aim to recover links between code and documentation, when the two fell out of sync. Objective: The aim of this paper is to compare the concepts contained within the source code of a system with those extracted from its documentation, in order to detect how similar these two sets are. If vastly different, the difference between the two sets might indicate a considerable ageing of the documentation, and a need to update it. Methods: In this paper we reduce the source code of 50 software systems to a set of key terms, each containing the concepts of one of the systems sampled. At the same time, we reduce the documentation of each system to another set of key terms. We then use four different approaches for set comparison to detect how the sets are similar. Results: Using the well known Jaccard index as the benchmark for the comparisons, we have discovered that the cosine distance has excellent comparative powers, and depending on the pre-training of the machine learning model. In particular, the SpaCy and the FastText embeddings offer up to 80% and 90% similarity scores. Conclusion: For most of the sampled systems, the source code and the documentation tend to contain very similar concepts. Given the accuracy for one pre-trained model (e.g., FastText), it becomes also evident that a few systems show a measurable drift between the concepts contained in the documentation and in the source code.</p

Using Immersive Virtual Reality for Student Learning: A Qualitative Case Study

ABSTRACT The prominence of virtual reality (VR) in the educational field has grown in recent years due to increased availability and lower costs. I conducted a global study regarding how pioneering K-12 teachers use VR to engage students in learning activities. The purpose of this qualitative case study was to identify how and why teachers used VR for student learning. Fifteen educators from five continents participated in the study. They described their initial VR experiences and how these experiences motivated them to pursue ways to implement VR in their disciplinary fields. I used the video conference tool “Zoom” to conduct interviews. Participants described the “spark” of discovery and recognition of VR for learning. They explained measures to obtain permission, approaches to funding, and the implementation process. Participants developed structures for student learning, transformed physical spaces, and invented pedagogies to ensure positive learning experiences. Participants provided optimal immersive experiences by repurposing content and adopting other applications to achieve learning goals. Three levels of incorporating VR for student learning were identified, including: (1) exploration; (2) acquiring and applying disciplinary knowledge; and (3) content creation and interactive problem solving. The quality of headsets dictated the level(s) of implementation. Dewey’s (1923) experiential learning theories as well as the Technology, Pedagogy, and Content Knowledge framework (TPACK; Mishra & Koehler, 2006) helped to interpret data. Successful implementation requires collaboration and pedagogical modifications and administrative support. This study highlights the successful methods and practices for others considering the implementation of VR for K-12 student learning. Keywords: TPACK, Dewey, Virtual Reality (VR), Innovation, Experiential Learnin