Approximation Algorithms for the Asymmetric Traveling Salesman Problem : Describing two recent methods

The paper provides a description of the two recent approximation algorithms for the Asymmetric Traveling Salesman Problem, giving the intuitive description of the works of Feige-Singh[1] and Asadpour et.al\ [2].\newline [1] improves the previous $O(\log n)$ approximation algorithm, by improving the constant from 0.84 to 0.66 and modifying the work of Kaplan et. al\ [3] and also shows an efficient reduction from ATSPP to ATSP. Combining both the results, they finally establish an approximation ratio of $\left(\frac{4}{3}+\epsilon \right)\log n$ for ATSPP,\ considering a small $\epsilon>0$,\ improving the work of Chekuri and Pal.[4]\newline Asadpour et.al, in their seminal work\ [2], gives an $O\left(\frac{\log n}{\log \log n}\right)$ randomized algorithm for the ATSP, by symmetrizing and modifying the solution of the Held-Karp relaxation problem and then proving an exponential family distribution for probabilistically constructing a maximum entropy spanning tree from a spanning tree polytope and then finally defining the thin-ness property and transforming a thin spanning tree into an Eulerian walk.\ The optimization methods used in\ [2] are quite elegant and the approximation ratio could further be improved, by manipulating the thin-ness of the cuts.Comment: 12 page

Effects of aggregate grading and admixtures/fillers on fresh and hardened properties of self-consolidating concrete

Self-consolidating concrete (SCC) is becoming a popular material in the concrete industry, due to ease of placement in congested reinforcement, reduced labor and equipment, nonsegregating character, and excellent surface finish. In spite of its several advantages, SCC is exceedingly sensitive to aggregate grading, size, admixtures, and filler contents. Though many studies have been conducted on rheological behavior of SCC, there is limited information on effects of aggregate size, grading, mineral admixture types, and fillers on durability, shrinkage and cracking properties.;In this study 17 SCC mixtures were initially developed using local aggregates, fly ash, slag, limestone fillers, commercial silica fume, viscosity-modifying admixtures (VMA), high-range water-reducing admixtures (HRWRA), shrinkage-reducing admixtures (SRA), and steel fibers. The mixtures were evaluated for slump-flow, visual stability, J-ring blocking test, L-box passing ability, and column static segregation. Comparisons of results with the concept of workability factors (representing fine fraction) and coarseness factor (representing coarse fraction) that were proposed for normal concrete, indicate that most of the rheological properties of SCC are strongly influenced by admixtures and fillers. Based on fresh properties and strength criteria, six best SCC were selected for in-depth study of strength development with time, free shrinkage, autogenous shrinkage, cracking potential, freeze-thaw, air-void parameters, and rapid chloride permeability.;Results show that compressive strength increased as water/powder ratio decreased and paste volume increased. The ACI prediction equation for limestone SCC underestimated the compressive strength with time. The shrinkage and cracking data showed that mixtures containing higher size of coarse aggregates (25 mm graded) had lower shrinkage and cracking potential compared to 12.5 mm graded aggregates. Autogenous shrinkage contributed significant portions of the total drying shrinkage measured. The data was calibrated for six existing models of shrinkage and finally a modified ACI based model was recommended for these SCC mixtures. SCC with coarse fractions of aggregate cracked later that those with finer fractions of aggregate. However, the inclusion of fibers and shrinkage reducing admixtures significantly reduced potential cracking, and SCC containing fibers improved the post-cracking behavior as well. Though the air-content of most SCC were higher than normal, the air-void parameters were within acceptable limits. This was confirmed by excellent resistance of SCC against freeze-thaw cycles and high durability factors obtained according to ASTM C 666 and C 215. Rapid chloride permeability values of SCC were adequate and close to regular HPC. Further studies on fracture parameters of hardened SCC are recommended. This should follow a full-scale implementation plan for specific structures and long-term monitoring

Why World Literature?:: Introductory Dialogues

In this issue, we acknowledge the phenomenal rise of world literature in current (Euro-American) literary studies. Although world literature as an object of study was revived in the 1990s, it was not till the last decade or so that scholars expressed such intense engagement with the issue

Speculation and Fiction

As students of literature, one of the most frequent questions we encounter is: how does one write anything? What are the factors responsible for writing fiction? Does fiction have its autonomous qualities? Put in a slightly different way: what is thought or how is thought put into fiction? Broadly speaking, the study into the domain of thought is speculation. The Oxford English dictionary defines “speculation” this way

Terror and the Literary:: An Introduction

Terror and terrorism are probably the most frequent catchwords of the contemporary times. At the turn of the century, Hardt and Negri warned us that we are living in a world of Empire as biopolitical production, where transnational corporations operate the mechanics of governance, and can wage ‘just war’ and resolve conflicts with the moral policing of the NGOs (2001: 22-41). Terror is part of the surveillance and regulation of life, while ‘terrorism,’ in its delimited political use, is only one way of engaging with it. Agamben’s notion of ‘state of exception’ in fuller picture indicates that the practice of life in contemporary times is a conscious response to fear of an unknown, unaccountable death which may not always be the death of the body as corpse. As Elizabeth Dauphinee and Christian Masters note: “Livings and dyings are ruptured by survivings that are neither livings nor dyings, but which are otherwise: liminal spaces of abjection that are dangerously difficult to recognize.” (2007: xvi) If contemporary bio-politics frames life from a normative position of mortality, as Badiou argues, its ethics foregrounds a ‘victimary’ notion of the human subject. The task for Badiou’s ethics is to counter-emphasize the ‘immortal’ in man where he treats a situation from the point which is impossible in relation to that situation. To treat the situation qua its impossible point is to change the situation and replace it with a new one and this highlights the subject’s immortality over the ephemeral situation. If this change is premised on the evental dimension of novelty, it encounters the impossible, which is not without its horizon of terror and trauma

Environment From a Humanities Perspective:: Introductory Thoughts

  In the last decades, there has begun a close and productive dialogue between humanities studies and environment and disaster studies. This has arisen from the general understanding in academic and policy-making circles that the problem of environmental crisis or of climate change cannot be meaningfully engaged with through the lens of one single discipline or for that matter through scientific studies alone

Democracy, Resistance, and the Practice of Literature:: Introduction

Recent world politics has witnessed the rise of a certain style of authoritarianism. It can be roughly characterized with a cult of masculine leadership, a popular rhetoric of foreign investment and development, and a phobia of the illegal immigrant made into an ethical obligation. These contradictory forms of politics – the paean to multinational corporations, free trade, and the ‘bloc’-ing of power and the simultaneous mobilization of hyper-nationalism in the form of censoring books and throttling subversive aesthetic practices – characterize the conception and practice of what may be called “authoritarian democracy.” Considering the democratically elected basis of this authoritarianism, it becomes all the more important to ask if democracy paves the way for it. In that case, where do we locate democracy today? Is it right to say that the real democratic space unfolds itself in people’s movements and not in the electoral process? If this is the case, a radical conception of democracy would have to account for a shift of emphasis from the locus of governance to that of resistance and co-option. Historically speaking, democracy may not always be the means but it has been one of the ends for the various acts of resistance such as the working class, anti-colonial, nationalist, feminist, LGBT, or constitutional multiculturalism. In our sour and hungry times, when state aggression is overpowering the geographical marking (Russia’s in Ukraine or Israel’s in Palestine), or strangling the voice of internal resistance (North Eastern regions in India), not to mention religious fundamentalism, we need to rethink the old questions of democracy and resistance. With the ISIS, Boko Haram or the Taliban practice, we have seen how resistance itself can produce a dangerous authoritarianism which further complicates the relations between democracy, authoritarianism, and resistance. How do we historicize and ethically theorize resistance in relation to both democracy and an authoritarianism which borders on fascism

Censorship and Literature:

The Oxford English Dictionary defines censorship as “the suppression or prohibition of any parts of books, films, news, etc. that are considered obscene, politically unacceptable, or a threat to security.”1 There is at least a two-fold meaning in this definition: first, certain factors give rise to censorship including obscenity, security, etc.

Nabarun Bhattacharya: An Introduction

Nabarun Bhattacharya was born in Calcutta in 1948 to Bijan Bhattacharya and Mahasweta Devi, both noted literary personalities