bluuebunny/crossref_metadata_2025_split huggingface dataset:
Unifiers as equivalences: proof-relevant unification of dependently typed data
Authors: Cockx Jesper , Devriese Dominique , Piessens Frank 
Published: December 2016

Dependently typed languages such as Agda, Coq and Idris use a syntactic first-order unification algorithm to check definitions by dependent pattern matching. However, these algorithms don’t adequately consider the types of the terms being unified, leading to various unintended results. As a consequence, they require ad hoc restrictions to preserve soundness, but this makes them very hard to prove correct, modify, or extend.
This paper proposes a framework for reasoning formally about unification in a dependently typed setting. In this framework, unification rules compute not just a unifier but also a corresponding correctness proof in the form of an equivalence between two sets of equations. By rephrasing the standard unification rules in a proof-relevant manner, they are guaranteed to preserve soundness of the theory. In addition, it enables us to safely add new rules that can exploit the dependencies between the types of equations.
Using our framework, we reimplemented the unification algorithm used by Agda. As a result, we were able to replace previous ad hoc restrictions with formally verified unification rules, fixing a number of bugs in the process. We are convinced this will also enable the addition of new and interesting unification rules in the future, without compromising soundness along the way.
Context-free session types
Authors: Thiemann Peter , Vasconcelos Vasco T. 
Published: December 2016

Session types describe structured communication on heterogeneously typed channels at a high level. Their tail-recursive structure imposes a protocol that can be described by a regular language. The types of transmitted values are drawn from the underlying functional language, abstracting from the details of serializing values of structured data types.
Context-free session types extend session types by allowing nested protocols that are not restricted to tail recursion. Nested protocols correspond to deterministic context-free languages. Such protocols are interesting in their own right, but they are particularly suited to describe the low-level serialization of tree-structured data in a type-safe way.
We establish the metatheory of context-free session types, prove that they properly generalize standard (two-party) session types, and take first steps towards type checking by showing that type equivalence is decidable.
Constructive Galois connections: taming the Galois connection framework for mechanized metatheory
Authors: Darais David , Van Horn David 
Published: December 2016

Galois connections are a foundational tool for structuring abstraction in semantics and their use lies at the heart of the theory of abstract interpretation. Yet, mechanization of Galois connections remains limited to restricted modes of use, preventing their general application in mechanized metatheory and certified programming.
This paper presents constructive Galois connections, a variant of Galois connections that is effective both on paper and in proof assistants; is complete with respect to a large subset of classical Galois connections; and enables more general reasoning principles, including the "calculational" style advocated by Cousot.
To design constructive Galois connection we identify a restricted mode of use of classical ones which is both general and amenable to mechanization in dependently-typed functional programming languages. Crucial to our metatheory is the addition of monadic structure to Galois connections to control a "specification effect". Effectful calculations may reason classically, while pure calculations have extractable computational content. Explicitly moving between the worlds of specification and implementation is enabled by our metatheory.
To validate our approach, we provide two case studies in mechanizing existing proofs from the literature: one uses calculational abstract interpretation to design a static analyzer, the other forms a semantic basis for gradual typing. Both mechanized proofs closely follow their original paper-and-pencil counterparts, employ reasoning principles not captured by previous mechanization approaches, support the extraction of verified algorithms, and are novel.
A type theory for incremental computational complexity with control flow changes
Authors: Çiçek Ezgi , Paraskevopoulou Zoe , Garg Deepak 
Published: December 2016

Incremental computation aims to speed up re-runs of a program after its inputs have been modified slightly. It works by recording a trace of the program's first run and propagating changes through the trace in incremental runs, trying to re-use as much of the original trace as possible. The recent work CostIt is a type and effect system to establish the time complexity of incremental runs of a program, as a function of input changes. However, CostIt is limited in two ways. First, it prohibits input changes that influence control flow. This makes it impossible to type programs that, for instance, branch on inputs that may change. Second, the soundness of CostIt is proved relative to an abstract cost semantics, but it is unclear how the semantics can be realized.
In this paper, we address both these limitations. We present DuCostIt, a re-design of CostIt, that combines reasoning about costs of change propagation and costs of from-scratch evaluation. The latter lifts the restriction on control flow changes. To obtain the type system, we refine Flow Caml, a type system for information flow analysis, with cost effects. Additionally, we inherit from CostIt index refinements to track data structure sizes and a co-monadic type. Using a combination of binary and unary step-indexed logical relations, we prove DuCostIt's cost analysis sound relative to not only an abstract cost semantics, but also a concrete semantics, which is obtained by translation to an ML-like language.
Chain: tasks and channels for reliable intermittent programs
Authors: Colin Alexei , Lucia Brandon 
Published: December 2016

Energy harvesting computers enable general-purpose computing using energy collected from their environment. Energy-autonomy of such devices has great potential, but their intermittent power supply poses a challenge. Intermittent program execution compromises progress and leaves state inconsistent. This work describes Chain: a new model for programming intermittent devices.
A Chain program is a set of programmer-defined tasks that compute and exchange data through channels. Chain guarantees forward progress at task granularity. A task is restartable and never sees inconsistent state, because its input and output channels are separated. Our system supports language features for expressing advanced data exchange patterns and for encapsulating reusable functionality.
Chain fundamentally differs from state-of-the-art checkpointing approaches and does not incur the associated overhead. We implement Chain as C language extensions and a runtime library. We used Chain to implement four applications: machine learning, encryption, compression, and sensing. In experiments, Chain ensured consistency where prior approaches failed and improved throughput by 2-7x over the leading state-of-the-art system.
Low-overhead and fully automated statistical debugging with abstraction refinement
Authors: Zuo Zhiqiang , Fang Lu , Khoo Siau-Cheng , Xu Guoqing , Lu Shan 
Published: December 2016

Cooperative statistical debugging is an effective approach for diagnosing production-run failures. To quickly identify failure predictors from the huge program predicate space, existing techniques rely on random or heuristics-guided predicate sampling at the user side. However, none of them can satisfy the requirements of low cost, low diagnosis latency, and high diagnosis quality simultaneously, which are all indispensable for statistical debugging to be practical.
This paper presents a new technique that tackles the above challenges. We formulate the technique as an instance of abstraction refinement, where efficient abstract-level profiling is first applied to the whole program and its execution brings information that can pinpoint suspicious coarse-grained entities that need to be refined. The refinement profiles a corresponding set of fine-grained entities, and generates feedback that determines what to prune and what to refine next. The process is fully automated, and more importantly, guided by a mathematically rigorous analysis that guarantees that our approach produces the same debugging results as an exhaustive analysis in deterministic settings.
We have implemented this technique for both C and Java on both single machine and distributed system. A thorough evaluation demonstrates that our approach yields (1) an order of magnitude reduction in the user-side runtime overhead even compared to a sampling-based approach and (2) two orders of magnitude reduction in the size of data transferred over the network, completely automatically without sacrificing any debugging capability.
A compiler for throughput optimization of graph algorithms on GPUs
Authors: Pai Sreepathi , Pingali Keshav 
Published: December 2016

Writing high-performance GPU implementations of graph algorithms can be challenging. In this paper, we argue that three optimizations called throughput optimizations are key to high-performance for this application class. These optimizations describe a large implementation space making it unrealistic for programmers to implement them by hand.
To address this problem, we have implemented these optimizations in a compiler that produces CUDA code from an intermediate-level program representation called IrGL. Compared to state-of-the-art handwritten CUDA implementations of eight graph applications, code generated by the IrGL compiler is up to 5.95x times faster (median 1.4x) for five applications and never more than 30% slower for the others. Throughput optimizations contribute an improvement up to 4.16x (median 1.4x) to the performance of unoptimized IrGL code.
Portable inter-workgroup barrier synchronisation for GPUs
Authors: Sorensen Tyler , Donaldson Alastair F. , Batty Mark , Gopalakrishnan Ganesh , Rakamarić Zvonimir 
Published: December 2016

Despite the growing popularity of GPGPU programming, there is not yet a portable and formally-specified barrier that one can use to synchronise across workgroups. Moreover, the occupancy-bound execution model of GPUs breaks assumptions inherent in traditional software execution barriers, exposing them to deadlock. We present an occupancy discovery protocol that dynamically discovers a safe estimate of the occupancy for a given GPU and kernel, allowing for a starvation-free (and hence, deadlock-free) inter-workgroup barrier by restricting the number of workgroups according to this estimate. We implement this idea by adapting an existing, previously non-portable, GPU inter-workgroup barrier to use OpenCL 2.0 atomic operations, and prove that the barrier meets its natural specification in terms of synchronisation.
We assess the portability of our approach over eight GPUs spanning four vendors, comparing the performance of our method against alternative methods. Our key findings include: (1) the recall of our discovery protocol is nearly 100%; (2) runtime comparisons vary substantially across GPUs and applications; and (3) our method provides portable and safe inter-workgroup synchronisation across the applications we study.
Finding compiler bugs via live code mutation
Authors: Sun Chengnian , Le Vu , Su Zhendong 
Published: December 2016

Validating optimizing compilers is challenging because it is hard to generate valid test programs (i.e., those that do not expose any undefined behavior). Equivalence Modulo Inputs (EMI) is an effective, promising methodology to tackle this problem. Given a test program with some inputs, EMI mutates the program to derive variants that are semantically equivalent w.r.t. these inputs. The state-of-the-art instantiations of EMI are Orion and Athena, both of which rely on deleting code from or inserting code into code regions that are not executed under the inputs. Although both have demonstrated their ability in finding many bugs in GCC and LLVM, they are still limited due to their mutation strategies that operate only on dead code regions.
This paper presents a novel EMI technique that allows mutation in the entire program (i.e., both live and dead regions). By removing the restriction of mutating only the dead regions, our technique significantly increases the EMI variant space. It also helps to more thoroughly stress test compilers as compilers must optimize mutated live code, whereas mutated dead code might be eliminated. Finally, our technique also makes compiler bugs more noticeable as miscompilations on mutated dead code may not be observable.
We have realized the proposed technique in Hermes. The evaluation demonstrates Hermes’s effectiveness. In 13 months, Hermes found 168 confirmed, valid bugs in GCC and LLVM, of which 132 have already been fixed.
Dynamin-related protein 1 mediates low glucose-induced endothelial dysfunction in human arterioles
Authors: Tanner Michael J. , Wang Jingli , Ying Rong , Suboc Tisha B. , Malik Mobin , Couillard Allison , Branum Amberly , Puppala Venkata , Widlansky Michael E. 
Published: December 2016

Intensive glycemic regulation has resulted in an increased incidence of hypoglycemia. Hypoglycemic burden correlates with adverse cardiovascular complications and contributes acutely and chronically to endothelial dysfunction. Prior data indicate that mitochondrial dysfunction contributes to hypoglycemia-induced endothelial dysfunction, but the mechanisms behind this linkage remain unknown. We attempt to determine whether clinically relevant low-glucose (LG) exposures acutely induce endothelial dysfunction through activation of the mitochondrial fission process. Characterization of mitochondrial morphology was carried out in cultured endothelial cells by using confocal microscopy. Isolated human arterioles were used to explore the effect LG-induced mitochondrial fission has on the formation of detrimental reactive oxygen species (ROS), bioavailability of nitric oxide (NO), and endothelial-dependent vascular relaxation. Fluorescence microscopy was employed to visualize changes in mitochondrial ROS and NO levels and videomicroscopy applied to measure vasodilation response. Pharmacological disruption of the profission protein Drp1 with Mdivi-1 during LG exposure reduced mitochondrial fragmentation among vascular endothelial cells (LG: 0.469; LG+Mdivi-1: 0.276; P = 0.003), prevented formation of vascular ROS (LG: 2.036; LG+Mdivi-1: 1.774; P = 0.005), increased the presence of NO (LG: 1.352; LG+Mdivi-1: 1.502; P = 0.048), and improved vascular dilation response to acetylcholine (LG: 31.6%; LG+Mdivi-1; 78.5% at maximum dose; P < 0.001). Additionally, decreased expression of Drp1 via siRNA knockdown during LG conditions also improved vascular relaxation. Exposure to LG imparts endothelial dysfunction coupled with altered mitochondrial phenotypes among isolated human arterioles. Disruption of Drp1 and subsequent mitochondrial fragmentation events prevents impaired vascular dilation, restores mitochondrial phenotype, and implicates mitochondrial fission as a primary mediator of LG-induced endothelial dysfunction. NEW & NOTEWORTHY Acute low-glucose exposure induces mitochondrial fragmentation in endothelial cells via Drp1 and is associated with impaired endothelial function in human arterioles. Targeting of Drp1 prevents fragmentation, improves vasofunction, and may provide a therapeutic target for improving cardiovascular complications among diabetics. Listen to this article’s corresponding podcast @ http://ajpheart.podbean.com/e/mitochondrial-dynamics-impact-endothelial-function/ .
miR‐17/20 Controls Prolyl Hydroxylase 2 (PHD2)/Hypoxia‐Inducible Factor 1 (HIF1) to Regulate Pulmonary Artery Smooth Muscle Cell Proliferation
Authors: Chen Tianji , Zhou Qiyuan , Tang Haiyang , Bozkanat Melike , Yuan Jason X.‐J. , Raj J. Usha , Zhou Guofei 
Published: December 2016

Background

Previously we found that smooth muscle cell (
SMC
)‐specific knockout of miR‐17~92 attenuates hypoxia‐induced pulmonary hypertension. However, the mechanism underlying miR‐17~92‐mediated pulmonary artery
SMC
(
PASMC
) proliferation remains unclear. We sought to investigate whether miR‐17~92 regulates hypoxia‐inducible factor (
HIF
) activity and
PASMC
proliferation via prolyl hydroxylases (
PHD
s).

Methods and Results

We show that hypoxic sm‐17~92
−/−
mice have decreased hematocrit, red blood cell counts, and hemoglobin contents. The sm‐17~92
−/−
mouse lungs express decreased
mRNA
levels of
HIF
targets and increased levels of
PHD
2. miR‐17~92 inhibitors suppress hypoxia‐induced levels of
HIF
1α,
VEGF
, Glut1,
HK
2, and
PDK
1 but not
HIF
2α in vitro in
PASMC
. Overexpression of miR‐17 in
PASMC
represses
PHD
2 expression, whereas miR‐17/20a inhibitors induce
PHD
2 expression. The 3′‐
UTR
of
PHD
2 contains a functional miR‐17/20a seed sequence. Silencing of
PHD
2 induces
HIF
1α and
PCNA
protein levels, whereas overexpression of
PHD
2 decreases
HIF
1α and cell proliferation.
SMC
‐specific knockout of
PHD
2 enhances hypoxia‐induced vascular remodeling and exacerbates established pulmonary hypertension in mice.
PHD
2 activator R59949 reverses vessel remodeling in existing hypertensive mice.
PHD
s are dysregulated in
PASMC
isolated from pulmonary arterial hypertension patients.

Conclusions

Our results suggest that
PHD
2 is a direct target of miR‐17/20a and that miR‐17~92 contributes to
PASMC
proliferation and polycythemia by suppression of
PHD
2 and induction of
HIF
1α.
The Qinghua “Jinteng” Manuscript: What it Does Not Tell Us about the Duke of Zhou
Authors: Ribbing Gren Magnus 
Published: December 2016

This study suggests that the so-called “Jinteng” manuscript held by Qinghua University should be read independently of its received counterpart. When read on its own terms, the manuscript provides a straightforward account of rituals surrounding the Duke of Zhou’s ascension to the throne after the demise of King Wu. As such it represents a continuation of King Wu’s abdication in favor of his meritorious brother, as recorded in the Yi Zhou shu. Read in this light, the fourth century BCE manuscript provides further evidence for the prominence of abdication doctrines during the Warring States period, an intellectual tradition that was deemed subversive in the early empire and became gradually obliterated over the course of the Qin-Han dynasties. Cet article propose de lire le manuscrit dit “Jinteng” conservé à l’université Qinghua indépendamment des textes reçus qui lui correspondent. Considéré par lui-même, le manuscrit offre une relation claire des rituels ayant entouré l’accession au trône du duc de Zhou après la mort du roi Wu. De ce fait, il représente le prolongement de l’abdication du roi Wu en faveur de son vertueux frère telle qu’elle est relatée dans le Yi Zhou shu. Considéré sous cet angle, ce manuscrit du IVe siècle avant notre ère offre de nouveaux arguments en faveur de l’importance des doctrines sur l’abdication à l’époque des Royaumes Combattants, alors que cette tradition intellectuelle était considérée comme subversive au début de l’empire et qu’elle est progressivement tombée dans l’oubli sous les Qin et les Han.
Taxonomic notes on the genera Brypoctia Schoorl, 1990 and Schreiteriana Fletcher &amp; Nye, 1982 (Lepidoptera, Cossidae)
Authors: PENCO FERNANDO C. , YAKOVLEV ROMAN V. , WITT THOMAS J. 
Published: December 2016

Currently, the Cossidae of South America are rather poorly studied. Data on the distribution and taxonomy of Neotropical carpenter moths are lacking. An exception is the clarification of the taxonomic position of the genus Miacora Dyar, 1905 (Yakovlev 2014), Neotropical Cossidae checklist (Donahue 1995), and a preliminary list of Cossidae of Argentina (Penco & Yakovlev 2015). The majority of Neotropical Cossidae genera have not been studied and the taxonomic position of some genera remains completely unresolved. Additionally, images of genitalia of the Neotropical genera have not been published, including the genera Brypoctia Schoorl, 1990 and Schreiteriana Fletcher & Nye, 1982 (Cossidae: Zeuzerinae). The taxonomic position of the second genus was questioned by Schoorl (1990).
Galeus corriganae sp. nov., a new species of deepwater catshark (Carcharhiniformes: Pentanchidae) from Papua New Guinea
Authors: WHITE WILLIAM T. , MANA RALPH R. , NAYLOR GAVIN J.P. 
Published: December 2016

A new species of catshark, provisionally placed in the genus Galeus, is described from Papua New Guinea based on 7 specimens collected during recent deepwater surveys of the region. The new species, Galeus corriganae, is closest to G. priapus from New Caledonia and G. gracilis from northwestern Australia but differs in several morphological characters. A reclassification of the catshark groups is required to revise the familial and generic arrangement of the group.
Treatment of Insertional Achilles Pathology With Dorsal Wedge Calcaneal Osteotomy in Athletes
Authors: Georgiannos Dimitrios , Lampridis Vasilis , Vasiliadis Angelos , Bisbinas Ilias 
Published: December 2016

Background: Insertional Achilles tendinopathy and retrocalcaneal bursitis is difficult to treat, and several operative techniques have been used after failure of conservative management. Dorsal wedge calcaneal osteotomy has been described for the treatment of insertional Achilles pathology. It was hypothesized that dorsal wedge calcaneal osteotomy would be an effective and safe method for the treatment of athletes with insertional Achilles pathology unrelieved by nonoperative measures. Methods: Fifty-two athletes (64 feet) who had painful Achilles tendon syndrome unrelieved by 6 months of nonoperative measures were treated surgically. Dorsally based wedge calcaneal osteotomy was performed through a lateral approach, and 2 staples were used for fixation. Patients were scored pre- and postoperatively with the American Orthopaedic Foot & Ankle Society (AOFAS) ankle-hindfoot and Victorian Institute of Sports of Australia-Achilles (VISA-A) scores. Results: At a minimum follow-up of 3 years, the patients’ AOFAS and VISA-A scores improved from 59.5 ± 15.0 and 65.9 ± 11.1 preoperatively to 95.7 ± 6.2 and 90.2 ± 8.4 postoperatively, respectively. Clinical results were considered excellent in 38 patients, good in 12 patients, and fair in 2 patients. Return to previous sports activity time was 21 (SD, 8.0) weeks. One patient necessitated a revision operation. Conclusion: Operative treatment of insertional Achilles pathology in athletes with dorsal closing wedge calcaneal osteotomy was a safe and effective method that allowed for a quicker return to previous level of sports activities compared with other techniques. Level of evidence: Level IV, retrospective case series