Even the simplest hardware, running the simplest programs, can behave in the strangest of ways. T... more Even the simplest hardware, running the simplest programs, can behave in the strangest of ways. Tracking down the cause of a performance anomaly without the complete hardware reference of a processor is a prime example of blackbox architectural exploration. When doubling the work of a simple benchmark program, that was run on a single core of Tilera's TILEPro64 processor, did not double the number of consumed cycles, a mystery was unveiled. After ruling out different levels of optimization for the two programs, a cycleaccurate simulation attributed the sub-optimal performance to an abnormally high number of L1 data cache misses. Further investigation showed that the processor stalled on every Read-After-Write instruction sequence when the following two conditions were met: 1) there are 0 or 1 instructions between the write and the read instruction and 2) the read and the write instructions target distinct memory locations that share an L1 cache line. We call this performance pitfall a RAW hiccup. We describe two countermeasures, memory padding and the explicit introduction of pipeline bubbles, that sidestep the RAW hiccup. This experience paper serves as a useful troubleshooting guide for uncovering anomalous performance issues when the hardware design under study is unavailable.
In today's software world with its cornucopia of reusable software libraries, when a programmer i... more In today's software world with its cornucopia of reusable software libraries, when a programmer is faced with a programming task that they suspect can be completed through the use of a library, they often look for code examples using a search engine and then manually adapt found examples to their specific context of use. We put forward a vision based on a new breed of developer tools that have the potential to largely automate this process. The key idea is to adapt code autocompletion tools such that they take into account not only the developer's already-written code but also the intent of the task the developer is trying to achieve next, formulated in plain natural language. We call this practice of enriching the code with natural language intent to facilitate its completion natural language-guided programming. To show that this idea is feasible we design, implement and benchmark a tool that solves this problem in the context of a specific domain (data science) and a specific programming language (Python). Central to the tool is the use of language models trained on a large corpus of documented code. Our initial experiments confirm the feasibility of the idea but also make it clear that we have only scratched the surface of what may become possible in the future. We end the paper with a comprehensive research agenda to stimulate additional research in the budding area of natural language-guided programming. CCS Concepts: • Software and its engineering → Integrated and visual development environments; • Computing methodologies → Natural language processing.
2019 IEEE/ACM 16th International Conference on Mining Software Repositories (MSR), 2019
We consider the problem of developing suitable learning representations (embeddings) for library ... more We consider the problem of developing suitable learning representations (embeddings) for library packages that capture semantic similarity among libraries. Such representations are known to improve the performance of downstream learning tasks (e.g. classification) or applications such as contextual search and analogical reasoning. We apply word embedding techniques from natural language processing (NLP) to train embeddings for library packages ("library vectors"). Library vectors represent libraries by similar context of use as determined by import statements present in source code. Experimental results obtained from training such embeddings on three large open source software corpora reveals that library vectors capture semantically meaningful relationships among software libraries, such as the relationship between frameworks and their plug-ins and libraries commonly used together within ecosystems such as big data infrastructure projects (in Java), front-end and back-end web development frameworks (in JavaScript) and data science toolkits (in Python).
In mobile ad hoc networks, distributed programming is substantially complicated by the fact that ... more In mobile ad hoc networks, distributed programming is substantially complicated by the fact that nodes in the network only have intermittent connectivity and the lack of any centralized coordination facility. Because transient disconnections are so omnipresent in mobile networks, we assume a distributed object-oriented programming model in which remote object references abstract over network disconnections by default. However, this language design decision has repercussions on distributed memory management, as disconnected remote references can prevent an object from being reclaimed. To address this issue, we integrate memory management based on leasing directly into the remote object reference abstraction, leading to the concept of a leased object reference. We explore the language design issues, the integration with other language features and illustrate the applicability of the language construct by means of a concrete example.
Debuggers are an integral part, albeit often neglected, of the development of distributed applica... more Debuggers are an integral part, albeit often neglected, of the development of distributed applications. Ambient-oriented programming (AmOP) is a distributed paradigm for applications running on mobile ad hoc networks. In AmOP the complexity of programming in a distributed setting is married with the network fragility and open topology of mobile applications. To our knowledge, there is no comprehensive debugging approach that tackles both these issues. In this paper we present REME-D, an online debugger that integrates techniques from distributed debugging (event-based debugging, message breakpoints) and proposes facilities to deal with ad hoc, fragile networks-epidemic debugging, and support for frequent disconnections. A prototype for REME-D is implemented for the AmbientTalk language using the meta-actor protocol provided by AmbientTalk to implement its features.
Mobile social networking applications enable end-users to interact on the move. Current applicati... more Mobile social networking applications enable end-users to interact on the move. Current applications model user groups as simple lists which have to be manually enumerated. This representation is both unsuitable and inefficient for group interactions: due to the openness and the mobility to which these applications are exposed, the contents of such lists are likely to change frequently. Updating the lists manually while interacting with users quickly becomes impractical. In this paper, we introduce an alternative representation for user groups named flocks. A flock represents a looselydefined user group in terms of an intensional description. The flock content is implicitly updated when changes occur, e.g. the users's location. Flocks have group interaction provisions based on asynchronous message passing. Benchmarks indicate that flocks can be implemented efficiently by exploiting structure in their definitions. We present the flock abstraction and its implementation as the basis of a new distributed framework called Urbiflock.
The version in the Kent Academic Repository may differ from the final published version. Users ar... more The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record.
Abstract Pervasive social applications are applications that enable end users to interact and sha... more Abstract Pervasive social applications are applications that enable end users to interact and share information on the move. In these applications, the concept of a user group plays a central role as it models the user's social networks. Most pervasive social applications ...
A new field in distributed computing, called Ambient Intelligence, has emerged as a consequence o... more A new field in distributed computing, called Ambient Intelligence, has emerged as a consequence of the increasing availability of wireless devices and the mobile networks they induce. Developing software for such mobile networks is extremely hard in conventional programming languages because the network is dynamically defined. This hardware phenomenon leads us to postulate a suite of characteristics of future Ambient-Oriented Programming languages. A simple reflective programming language kernel, called Am-bientTalk, that meets these characteristics is subsequently presented. The power of the reflective kernel is illustrated by using it to conceive a collection of high level tentative ambient-oriented programming language features.
The development of programs for mobile devices inhabiting Ambient Intelligent network constellati... more The development of programs for mobile devices inhabiting Ambient Intelligent network constellations is notoriously difficult. These difficulties stem from the fact that the limitations imposed by the hardware need to be dealt with in an ad hoc fashion. In this paper we advocate the use of conversations as a general programming model to develop applications for Ambient Intelligence. We illustrate how conversations tackle the different concerns of ambient-oriented software development.
Proceedings of the 6th international workshop on Middleware for pervasive and ad-hoc computing, 2008
ABSTRACT Extensions to the actor model have been proposed to ease the development of mobile ad ho... more ABSTRACT Extensions to the actor model have been proposed to ease the development of mobile ad hoc applications. However, programming in the actor model is still difficult as it does not provide abstractions to synchronously coordinate multiple actors. Thus, when programmers want to coordinate two or more actors they have to do it by hand. Additionally, programmers need to write failure recovery code for failures caused by the concurrent access to the actors they are using. Coding this manually is error prone and might even be not feasible. We propose a language abstraction based on software transactional memory to coordinate actors. We show that the integration of software transactional memory with the actor model makes writing failure recovery code superfluous. Moreover, we show that our system even handles those cases where manually writing the failure recovery code is not feasible.
potsdam.de In this position paper we propose to extend an existing delegation-based machine model... more potsdam.de In this position paper we propose to extend an existing delegation-based machine model with concurrency primi-tives. The original machine model which is built on the con-cepts of objects, messages, and delegation, provides support for languages enabling multi-dimensional separation of con-cerns (MDSOC). We propose to extend this model with an actor-based concurrency model, allowing for both true par-allelism as well as lightweight concurrency primitives such as coroutines. In order to demonstrate its expressiveness, we informally describe how three high-level languages sup-porting different concurrency models can be mapped onto our extended machine model. We also provide an outlook on the extended model’s potential to support concurrency-related MDSOC features. 1.
Fork/Join parallelism based on work stealing is becoming a widely used approach for parallelizing... more Fork/Join parallelism based on work stealing is becoming a widely used approach for parallelizing programs, yielding good and proven performance characteristics, while being relatively convenient to use. A known problem, however, is that randomized work stealing may suffer from suboptimal data locality over time. Current solutions for this issue rely on programmers defining worker affinity for tasks, or defining locales or places where tasks can be explicitly placed when they are generated. They thus add cognitive overhead. In this position paper, we propose to complement these existing solutions with a domain-specific approach: Based on the observation that most parallel algorithms can be classified according to “dwarfs”, we suggest to include explicit support for such classes of algorithms on top of the basic Fork/Join operations. Such additional support (in terms of language constructs or library extensions) can improve data locality based on domain-specific knowledge such as how...
The connected car is likely to play a fundamental role in the foreseeable Internet of Things. The... more The connected car is likely to play a fundamental role in the foreseeable Internet of Things. The connectivity aspect in combination with the available data (e.g. from GPS, on-board diagnostics, road sensors) and video (e.g. from dashcams and traffic cameras) streams enable a range of new applications, e.g., accident avoidance, online route planning, energy optimization, etc. These applications, however, come with an additional set of requirements which are not accommodated by the state-of-the-art stream processing platforms. We have built World-Wide Streams (WWS), a novel stream processing platform that has been explicitly designed with those requirements in mind. In this demo presentation, we will show a number of connected car scenarios that we have built on top of WWS.
Functional Reactive Programming (FRP) is a model of reactive programming defined by having a well... more Functional Reactive Programming (FRP) is a model of reactive programming defined by having a well-defined semantics given by time-indexed values. Promises are one-shot communication channels which allow asynchronous programs to be written in a synchronous style. In this paper, we show how timed promise lists, a timestamped linked list structure using promises rather than pointers, can be used to implement FRP. This idea originated with Elliott’s Push/Pull FRP, and we show that it can be expressed idiomatically in a strict functional language with promises, JavaScript. We identify a potential space leak with JavaScript’s built-in promises and propose an alternative implementation that avoids the leak.
The actor model is a message-passing concurrency model that avoids deadlocks and low-level data r... more The actor model is a message-passing concurrency model that avoids deadlocks and low-level data races by construction. This facilitates concurrent programming, especially in the context of complex interactive applications where modularity, security and fault-tolerance are required. The tradeoff is that the actor model sacrifices expressiveness and safety guarantees with respect to parallel access to shared state. In this paper we present domains as a set of novel language abstractions for safely encapsulating and sharing state within the actor model. We introduce four types of domains, namely immutable, isolated, observable and shared domains that each are tailored to a certain access pattern on that shared state. The domains are characterized with an operational semantics. For each we discuss how the actor model's safety guarantees are upheld even in the presence of conceptually shared state. Furthermore, the proposed language abstractions are evaluated with a case study in Scala comparing them to other synchonisation mechanisms to demonstrate their benefits in deadlock freedom, parallel reads, and enforced isolation.
Electronic Proceedings in Theoretical Computer Science, 2010
Recent data on the high-p T pion nuclear modification factor, R AA (p T), and its elliptic azimut... more Recent data on the high-p T pion nuclear modification factor, R AA (p T), and its elliptic azimuthal asymmetry, v 2 (p T), from RHIC/BNL and LHC/CERN are analyzed in terms of a wide class of jet-energy loss models coupled to different (2+1)d transverse plus Bjorken expanding hydrodynamic fields. We test the consistency of each model by demanding a simultaneous account of the azimuthal, the transverse momentum, and the centrality dependence of the data at both 0.2 and 2.76 ATeV energies. We find a rather broad class of jet-energy independent energy-loss models dE/dx = κ(T)x z T 2+z ζ q that, when coupled to bulk constrained temperature fields T (x, t), can account for the current data at the χ 2 /d.o.f. < 2 level with different temperature-dependent jet-medium couplings, κ(T), and path-length dependence exponents 0 ≤ z ≤ 2. We extend previous studies by including a generic term, 0 < ζ q < 2 + q, to test different scenarios of energy-loss fluctuations. While a previously proposed AdS/CFT jet-energy loss model with a temperature-independent jet-medium coupling as well as a near-T c dominated, pQCD-inspired energy-loss scenario are shown to be inconsistent with the LHC data, once the parameters are constrained by fitting to RHIC results, we find several new solutions with a temperature-dependent κ(T). We conclude that the current level of statistical and systematic uncertainties of the measured data does not allow a constraint on the path-length exponent z to a range narrower than [0 − 2].
Even the simplest hardware, running the simplest programs, can behave in the strangest of ways. T... more Even the simplest hardware, running the simplest programs, can behave in the strangest of ways. Tracking down the cause of a performance anomaly without the complete hardware reference of a processor is a prime example of blackbox architectural exploration. When doubling the work of a simple benchmark program, that was run on a single core of Tilera's TILEPro64 processor, did not double the number of consumed cycles, a mystery was unveiled. After ruling out different levels of optimization for the two programs, a cycleaccurate simulation attributed the sub-optimal performance to an abnormally high number of L1 data cache misses. Further investigation showed that the processor stalled on every Read-After-Write instruction sequence when the following two conditions were met: 1) there are 0 or 1 instructions between the write and the read instruction and 2) the read and the write instructions target distinct memory locations that share an L1 cache line. We call this performance pitfall a RAW hiccup. We describe two countermeasures, memory padding and the explicit introduction of pipeline bubbles, that sidestep the RAW hiccup. This experience paper serves as a useful troubleshooting guide for uncovering anomalous performance issues when the hardware design under study is unavailable.
In today's software world with its cornucopia of reusable software libraries, when a programmer i... more In today's software world with its cornucopia of reusable software libraries, when a programmer is faced with a programming task that they suspect can be completed through the use of a library, they often look for code examples using a search engine and then manually adapt found examples to their specific context of use. We put forward a vision based on a new breed of developer tools that have the potential to largely automate this process. The key idea is to adapt code autocompletion tools such that they take into account not only the developer's already-written code but also the intent of the task the developer is trying to achieve next, formulated in plain natural language. We call this practice of enriching the code with natural language intent to facilitate its completion natural language-guided programming. To show that this idea is feasible we design, implement and benchmark a tool that solves this problem in the context of a specific domain (data science) and a specific programming language (Python). Central to the tool is the use of language models trained on a large corpus of documented code. Our initial experiments confirm the feasibility of the idea but also make it clear that we have only scratched the surface of what may become possible in the future. We end the paper with a comprehensive research agenda to stimulate additional research in the budding area of natural language-guided programming. CCS Concepts: • Software and its engineering → Integrated and visual development environments; • Computing methodologies → Natural language processing.
2019 IEEE/ACM 16th International Conference on Mining Software Repositories (MSR), 2019
We consider the problem of developing suitable learning representations (embeddings) for library ... more We consider the problem of developing suitable learning representations (embeddings) for library packages that capture semantic similarity among libraries. Such representations are known to improve the performance of downstream learning tasks (e.g. classification) or applications such as contextual search and analogical reasoning. We apply word embedding techniques from natural language processing (NLP) to train embeddings for library packages ("library vectors"). Library vectors represent libraries by similar context of use as determined by import statements present in source code. Experimental results obtained from training such embeddings on three large open source software corpora reveals that library vectors capture semantically meaningful relationships among software libraries, such as the relationship between frameworks and their plug-ins and libraries commonly used together within ecosystems such as big data infrastructure projects (in Java), front-end and back-end web development frameworks (in JavaScript) and data science toolkits (in Python).
In mobile ad hoc networks, distributed programming is substantially complicated by the fact that ... more In mobile ad hoc networks, distributed programming is substantially complicated by the fact that nodes in the network only have intermittent connectivity and the lack of any centralized coordination facility. Because transient disconnections are so omnipresent in mobile networks, we assume a distributed object-oriented programming model in which remote object references abstract over network disconnections by default. However, this language design decision has repercussions on distributed memory management, as disconnected remote references can prevent an object from being reclaimed. To address this issue, we integrate memory management based on leasing directly into the remote object reference abstraction, leading to the concept of a leased object reference. We explore the language design issues, the integration with other language features and illustrate the applicability of the language construct by means of a concrete example.
Debuggers are an integral part, albeit often neglected, of the development of distributed applica... more Debuggers are an integral part, albeit often neglected, of the development of distributed applications. Ambient-oriented programming (AmOP) is a distributed paradigm for applications running on mobile ad hoc networks. In AmOP the complexity of programming in a distributed setting is married with the network fragility and open topology of mobile applications. To our knowledge, there is no comprehensive debugging approach that tackles both these issues. In this paper we present REME-D, an online debugger that integrates techniques from distributed debugging (event-based debugging, message breakpoints) and proposes facilities to deal with ad hoc, fragile networks-epidemic debugging, and support for frequent disconnections. A prototype for REME-D is implemented for the AmbientTalk language using the meta-actor protocol provided by AmbientTalk to implement its features.
Mobile social networking applications enable end-users to interact on the move. Current applicati... more Mobile social networking applications enable end-users to interact on the move. Current applications model user groups as simple lists which have to be manually enumerated. This representation is both unsuitable and inefficient for group interactions: due to the openness and the mobility to which these applications are exposed, the contents of such lists are likely to change frequently. Updating the lists manually while interacting with users quickly becomes impractical. In this paper, we introduce an alternative representation for user groups named flocks. A flock represents a looselydefined user group in terms of an intensional description. The flock content is implicitly updated when changes occur, e.g. the users's location. Flocks have group interaction provisions based on asynchronous message passing. Benchmarks indicate that flocks can be implemented efficiently by exploiting structure in their definitions. We present the flock abstraction and its implementation as the basis of a new distributed framework called Urbiflock.
The version in the Kent Academic Repository may differ from the final published version. Users ar... more The version in the Kent Academic Repository may differ from the final published version. Users are advised to check http://kar.kent.ac.uk for the status of the paper. Users should always cite the published version of record.
Abstract Pervasive social applications are applications that enable end users to interact and sha... more Abstract Pervasive social applications are applications that enable end users to interact and share information on the move. In these applications, the concept of a user group plays a central role as it models the user&amp;amp;amp;#x27;s social networks. Most pervasive social applications ...
A new field in distributed computing, called Ambient Intelligence, has emerged as a consequence o... more A new field in distributed computing, called Ambient Intelligence, has emerged as a consequence of the increasing availability of wireless devices and the mobile networks they induce. Developing software for such mobile networks is extremely hard in conventional programming languages because the network is dynamically defined. This hardware phenomenon leads us to postulate a suite of characteristics of future Ambient-Oriented Programming languages. A simple reflective programming language kernel, called Am-bientTalk, that meets these characteristics is subsequently presented. The power of the reflective kernel is illustrated by using it to conceive a collection of high level tentative ambient-oriented programming language features.
The development of programs for mobile devices inhabiting Ambient Intelligent network constellati... more The development of programs for mobile devices inhabiting Ambient Intelligent network constellations is notoriously difficult. These difficulties stem from the fact that the limitations imposed by the hardware need to be dealt with in an ad hoc fashion. In this paper we advocate the use of conversations as a general programming model to develop applications for Ambient Intelligence. We illustrate how conversations tackle the different concerns of ambient-oriented software development.
Proceedings of the 6th international workshop on Middleware for pervasive and ad-hoc computing, 2008
ABSTRACT Extensions to the actor model have been proposed to ease the development of mobile ad ho... more ABSTRACT Extensions to the actor model have been proposed to ease the development of mobile ad hoc applications. However, programming in the actor model is still difficult as it does not provide abstractions to synchronously coordinate multiple actors. Thus, when programmers want to coordinate two or more actors they have to do it by hand. Additionally, programmers need to write failure recovery code for failures caused by the concurrent access to the actors they are using. Coding this manually is error prone and might even be not feasible. We propose a language abstraction based on software transactional memory to coordinate actors. We show that the integration of software transactional memory with the actor model makes writing failure recovery code superfluous. Moreover, we show that our system even handles those cases where manually writing the failure recovery code is not feasible.
potsdam.de In this position paper we propose to extend an existing delegation-based machine model... more potsdam.de In this position paper we propose to extend an existing delegation-based machine model with concurrency primi-tives. The original machine model which is built on the con-cepts of objects, messages, and delegation, provides support for languages enabling multi-dimensional separation of con-cerns (MDSOC). We propose to extend this model with an actor-based concurrency model, allowing for both true par-allelism as well as lightweight concurrency primitives such as coroutines. In order to demonstrate its expressiveness, we informally describe how three high-level languages sup-porting different concurrency models can be mapped onto our extended machine model. We also provide an outlook on the extended model’s potential to support concurrency-related MDSOC features. 1.
Fork/Join parallelism based on work stealing is becoming a widely used approach for parallelizing... more Fork/Join parallelism based on work stealing is becoming a widely used approach for parallelizing programs, yielding good and proven performance characteristics, while being relatively convenient to use. A known problem, however, is that randomized work stealing may suffer from suboptimal data locality over time. Current solutions for this issue rely on programmers defining worker affinity for tasks, or defining locales or places where tasks can be explicitly placed when they are generated. They thus add cognitive overhead. In this position paper, we propose to complement these existing solutions with a domain-specific approach: Based on the observation that most parallel algorithms can be classified according to “dwarfs”, we suggest to include explicit support for such classes of algorithms on top of the basic Fork/Join operations. Such additional support (in terms of language constructs or library extensions) can improve data locality based on domain-specific knowledge such as how...
The connected car is likely to play a fundamental role in the foreseeable Internet of Things. The... more The connected car is likely to play a fundamental role in the foreseeable Internet of Things. The connectivity aspect in combination with the available data (e.g. from GPS, on-board diagnostics, road sensors) and video (e.g. from dashcams and traffic cameras) streams enable a range of new applications, e.g., accident avoidance, online route planning, energy optimization, etc. These applications, however, come with an additional set of requirements which are not accommodated by the state-of-the-art stream processing platforms. We have built World-Wide Streams (WWS), a novel stream processing platform that has been explicitly designed with those requirements in mind. In this demo presentation, we will show a number of connected car scenarios that we have built on top of WWS.
Functional Reactive Programming (FRP) is a model of reactive programming defined by having a well... more Functional Reactive Programming (FRP) is a model of reactive programming defined by having a well-defined semantics given by time-indexed values. Promises are one-shot communication channels which allow asynchronous programs to be written in a synchronous style. In this paper, we show how timed promise lists, a timestamped linked list structure using promises rather than pointers, can be used to implement FRP. This idea originated with Elliott’s Push/Pull FRP, and we show that it can be expressed idiomatically in a strict functional language with promises, JavaScript. We identify a potential space leak with JavaScript’s built-in promises and propose an alternative implementation that avoids the leak.
The actor model is a message-passing concurrency model that avoids deadlocks and low-level data r... more The actor model is a message-passing concurrency model that avoids deadlocks and low-level data races by construction. This facilitates concurrent programming, especially in the context of complex interactive applications where modularity, security and fault-tolerance are required. The tradeoff is that the actor model sacrifices expressiveness and safety guarantees with respect to parallel access to shared state. In this paper we present domains as a set of novel language abstractions for safely encapsulating and sharing state within the actor model. We introduce four types of domains, namely immutable, isolated, observable and shared domains that each are tailored to a certain access pattern on that shared state. The domains are characterized with an operational semantics. For each we discuss how the actor model's safety guarantees are upheld even in the presence of conceptually shared state. Furthermore, the proposed language abstractions are evaluated with a case study in Scala comparing them to other synchonisation mechanisms to demonstrate their benefits in deadlock freedom, parallel reads, and enforced isolation.
Electronic Proceedings in Theoretical Computer Science, 2010
Recent data on the high-p T pion nuclear modification factor, R AA (p T), and its elliptic azimut... more Recent data on the high-p T pion nuclear modification factor, R AA (p T), and its elliptic azimuthal asymmetry, v 2 (p T), from RHIC/BNL and LHC/CERN are analyzed in terms of a wide class of jet-energy loss models coupled to different (2+1)d transverse plus Bjorken expanding hydrodynamic fields. We test the consistency of each model by demanding a simultaneous account of the azimuthal, the transverse momentum, and the centrality dependence of the data at both 0.2 and 2.76 ATeV energies. We find a rather broad class of jet-energy independent energy-loss models dE/dx = κ(T)x z T 2+z ζ q that, when coupled to bulk constrained temperature fields T (x, t), can account for the current data at the χ 2 /d.o.f. < 2 level with different temperature-dependent jet-medium couplings, κ(T), and path-length dependence exponents 0 ≤ z ≤ 2. We extend previous studies by including a generic term, 0 < ζ q < 2 + q, to test different scenarios of energy-loss fluctuations. While a previously proposed AdS/CFT jet-energy loss model with a temperature-independent jet-medium coupling as well as a near-T c dominated, pQCD-inspired energy-loss scenario are shown to be inconsistent with the LHC data, once the parameters are constrained by fitting to RHIC results, we find several new solutions with a temperature-dependent κ(T). We conclude that the current level of statistical and systematic uncertainties of the measured data does not allow a constraint on the path-length exponent z to a range narrower than [0 − 2].
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Papers by Tom Van Cutsem