Session Type Inference in Haskell

We present an inference system for a version of the Pi-calculus in Haskell for the session type proposed by Honda et al. The session type is very useful in checking if the communications are well-behaved. The full session type implementation in Haskell was first presented by Pucella and Tov, which is 'semi-automatic' in that the manual operations for the type representation was necessary. We give an automatic type inference for the session type by using a more abstract representation for the session type based on the 'de Bruijn levels'. We show an example of the session type inference for a simple SMTP client.Comment: In Proceedings PLACES 2010, arXiv:1110.385

Take up DNSSEC When Needed

The threats of caching poisoning attacks largely stimulate the deployment of DNSSEC. Being a strong but demanding cryptographical defense, DNSSEC has its universal adoption predicted to go through a lengthy transition. Thus the DNSSEC practitioners call for a secure yet lightweight solution to speed up DNSSEC deployment while offering an acceptable DNSSEC-like defense. This paper proposes a new defense against cache poisoning attacks, still using but lightly using DNSSEC. In the solution, DNS operates in the DNSSEC-oblivious mode unless a potential attack is detected and triggers a switch to the DNSSEC-aware mode. The performance of the defense is analyzed and validated. The modeling checking results demonstrate that only a small DNSSEC query load is needed to ensure a small enough cache poisoning success rate

Simple Baseline for Visual Question Answering

We describe a very simple bag-of-words baseline for visual question answering. This baseline concatenates the word features from the question and CNN features from the image to predict the answer. When evaluated on the challenging VQA dataset [2], it shows comparable performance to many recent approaches using recurrent neural networks. To explore the strength and weakness of the trained model, we also provide an interactive web demo and open-source code. .Comment: One comparison method's scores are put into the correct column, and a new experiment of generating attention map is adde

Learning Program Embeddings to Propagate Feedback on Student Code

Providing feedback, both assessing final work and giving hints to stuck students, is difficult for open-ended assignments in massive online classes which can range from thousands to millions of students. We introduce a neural network method to encode programs as a linear mapping from an embedded precondition space to an embedded postcondition space and propose an algorithm for feedback at scale using these linear maps as features. We apply our algorithm to assessments from the Code.org Hour of Code and Stanford University's CS1 course, where we propagate human comments on student assignments to orders of magnitude more submissions.Comment: Accepted to International Conference on Machine Learning (ICML 2015

NXNSAttack: Recursive DNS Inefficiencies and Vulnerabilities

This paper exposes a new vulnerability and introduces a corresponding attack, the NoneXistent Name Server Attack (NXNSAttack), that disrupts and may paralyze the DNS system, making it difficult or impossible for Internet users to access websites, web e-mail, online video chats, or any other online resource. The NXNSAttack generates a storm of packets between DNS resolvers and DNS authoritative name servers. The storm is produced by the response of resolvers to unrestricted referral response messages of authoritative name servers. The attack is significantly more destructive than NXDomain attacks (e.g., the Mirai attack): i) It reaches an amplification factor of more than 1620x on the number of packets exchanged by the recursive resolver. ii) In addition to the negative cache, the attack also saturates the 'NS' section of the resolver caches. To mitigate the attack impact, we propose an enhancement to the recursive resolver algorithm, MaxFetch(k), that prevents unnecessary proactive fetches. We implemented the MaxFetch(1) mitigation enhancement on a BIND resolver and tested it on real-world DNS query datasets. Our results show that MaxFetch(1) degrades neither the recursive resolver throughput nor its latency. Following the discovery of the attack, a responsible disclosure procedure was carried out, and several DNS vendors and public providers have issued a CVE and patched their systems

Walking Through Jelly: Language Proficiency, Emotions, and Disrupted Collaboration in Global Work

In an ethnographic study comprised of interviews and concurrent observations of 145 globally distributed members of nine project teams of an organization, we found that uneven proficiency in English, the lingua franca, disrupted collaboration for both native and non-native speakers. Although all team members spoke English, different levels of fluency contributed to tensions on these teams. As non-native English speakers attempted to counter the apprehension they felt when having to speak English and native English speakers fought against feeling excluded and devalued, a cycle of negative emotion ensued and disrupted interpersonal relationships on these teams. We describe in detail how emotions and actions evolved recursively as coworkers sought to relieve themselves of negative emotions prompted by the lingua franca mandate and inadvertently behaved in ways that triggered negative responses in distant coworkers. Our results add to the scant literature on the role of emotions in collaborative relationships in organizations and suggest that organizational policies can set in motion a cycle of negative emotions that interfere with collaborative work.

Tasks that promote functional reasoning in early elementary school

Algebra is often described as the gateway to higher mathematics (Carpenter, Franke, & Levi, 2003; Kaput, 2008; Kaput & Blanton, 2001; Mason, 2008). Unfortunately, many students do not navigate this gateway successfully. Kaput (2008) and Mason (2008) suggested that this is due in part to the abrupt switch from arithmetic to algebra that occurs in late middle school to early high school. Many called for a change in the way mathematics is taught from kindergarten through high school (Blanton, 2008; Kaput, 2008; NCTM, 2000), which included a change to the introduction of early algebra. Carraher, Schliemann and Schwartz (2008) caution that early algebra is different from algebra early. They suggested that this was a switch in the way the basic tenants of algebraic thinking is understood, including generalizing arithmetic and functional thinking (Brizuela & Lara-Roth, 2002; Warren, 2005b). Given this focus on functional reasoning in early elementary school, I conducted a study of students in the third through fifth grades. My purpose was to identify the characteristics of functional reasoning tasks that promoted the development of functional reasoning. I also wanted to discover the ways in which students used these characteristics as they worked on a task. Another important aspect of this study was to find any other influences on the types and frequencies of generalizations the students constructed. My study lasted for 10 weeks during an afterschool enrichment program called On Track Learn Math. The program occurred on two days during the week and students worked on a different task per week across two five-week sessions. This study analyzed 10 of those tasks. The data demonstrated that the tasks contained specific characteristics that promoted the development of functional reasoning. The two most noteworthy considerations were that grade level and the complexity of the function rule affected the frequency with which students constructed explicit rules. The results of this study have implications on student learning, teacher practice, and curricular changes

Idaho National Lab Impedance Measurement Box High Voltage Coupling Circuit

Our project goal is to build a 300V [1] coupling circuit for the Idaho National Lab’s (INL) Impedance Measurement Box (IMB). The IMB is a device that determines the frequency spectrum of the internal impedance of a battery by measuring its impedance to various frequencies. The procedure involves the box outputting a sum of sines (SOS) signal into a battery, capturing its voltage response, and processing the voltage time record into an impedance spectrum. This allows the box to determine the internal impedance of the battery, which can be used to predict the battery’s life and other characteristics. [2] The IMB is currently built to measure batteries of up to 50V. Our goal is to design and construct a circuit that will allow the box to measure batteries of up to 300V. This will be done through the use of a coupling circuit and a state machine. The coupling circuit will operate by using a high voltage capacitor and resistors to protect the IMB and allow it to measure the battery without the source voltage ever exceeding 30V, which is the max the future IMB is designed to safely handl

Beyond XSPEC: Towards Highly Configurable Analysis

We present a quantitative comparison between software features of the defacto standard X-ray spectral analysis tool, XSPEC, and ISIS, the Interactive Spectral Interpretation System. Our emphasis is on customized analysis, with ISIS offered as a strong example of configurable software. While noting that XSPEC has been of immense value to astronomers, and that its scientific core is moderately extensible--most commonly via the inclusion of user contributed "local models"--we identify a series of limitations with its use beyond conventional spectral modeling. We argue that from the viewpoint of the astronomical user, the XSPEC internal structure presents a Black Box Problem, with many of its important features hidden from the top-level interface, thus discouraging user customization. Drawing from examples in custom modeling, numerical analysis, parallel computation, visualization, data management, and automated code generation, we show how a numerically scriptable, modular, and extensible analysis platform such as ISIS facilitates many forms of advanced astrophysical inquiry.Comment: Accepted by PASP, for July 2008 (15 pages