Session types

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Linearly Refined Session Types

Linearly Refined Session Types

The recent work by Toninho et al. [17] interprets session types within intuitionistic linear logic, obtaining (with some extensions) a dependent sessions type system for π -calculus. This system interprets session types as linear logic formulae, with input as ⊸ and output as ⊗, and stratifies the language into a π-calculus for communication and a functional language for proof objects, where the latter are opaque terms that (in our system) would correspond to proofs of refinements. However, their system does not consider linear refinements, i.e., linearity is restricted to the communication layer (the sessions). Although the aims of both systems are similar to an extent, we have taken a different approach, adopting session types without their linear-formulae interpretation, and focussing on the incorporation of fine- grained linear refinements which provide for a more delicate distinction between types. Moreover, we do not utilise proof-witnesses but rather implement proof search within the type system itself; then, using the heating relation, assumptions are manipulated at runtime in order to check assertions, which is essentially a procedure of cut-elimination.
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Modular session types for objects

Modular session types for objects

Clearly, correctness of the code in Figure 3 requires that the sequence of method calls on field file within class FileReader matches the available methods in the session type of class File , and that the appropriate switch or while loops are performed when prescribed by session types of the form h ... i in class File . Our static type system, defined in Section 3, enables this consistency to be checked at compile-time. A distinctive feature of our type system is that methods are checked in a precise order: that prescribed by the session type ( init , read, toString in class FileReader , Figure 3). As such the type of the private reference file always has the right type (and no further annotations—pre/post conditions—are required when in presence of non-recursive methods). Also, in order to check statically that an object with a dynamic interface such as file is used correctly, our type system treats the reference linearly so that aliases to it cannot be created. This restriction is not a problem for a simple example such as this one, but there is a considerable literature devoted to more flexible approaches to unique ownership. We discuss this issue further in Sections 4.6, 9 and 10.
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A concurrent programming language with session types

A concurrent programming language with session types

Ng et al. presented a programming framework for message-passing parallel algorithms which combines session types with the C programming language, called Session C [28]. This multiparty session-based programming environment ensures deadlock freedom, com- munication safety and global progress for well-typed programs. A Session C program is a C program that uses communication primitives based on the theory of session types. Besides the usual operations to send and receive values, Session C also includes multicast sending and multicast receiving primitives, where the first one sends the same message to all receivers and the second one receives messages from multiples senders. It also provides a branching operation where a programmer may define different communica- tion behaviours (different options) for a participant according to what option is selected by another participant. Finally, this implementation also provides two methods for iter- ation: local and communicating. A local iteration is similar to a while statement and a communicating iteration is a distributed version of a loop to support multicast.
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A type checking algorithm for qualified session types

A type checking algorithm for qualified session types

More in detail, type checking relies on the definition of several unambiguous patterns. The patterns for linear input and output processes do return a marked context. In the body of the function a recursive call to type check the continuation is launched. If an exception is not raised, this call returns in output a context. First, to ensure a subsequent linear usage to be finished within the continuation we verify the type for the variable in the context to be unrestricted. Second, to prohibit the use of the variable in the next thread we return a context with an “unusable” mark for the type of the variable. Similarly, in delegating a channel end of a session we pass to the checking function for the continuation a context with an unusable mark for the delegated type. Under replication, we do no admit to return new typings marked as unusable, which would imply consumption of a linear resource. Lastly, the algorithm succeeds if the context returned by the top-level call of the type checking function does not contain linear types.
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A Logical Foundation for Session-based Concurrent Computation

A Logical Foundation for Session-based Concurrent Computation

Polymorphism for process calculi has been studied extensively in the literature. However, our work seems to be the first developing termination and relational parametricity results for polymorphic session types, by relying solely on linear logic principles. Turner [78] investigated a form of polymorphism based only on existential quantification for a simply-typed π-calculus (roughly, the discipline in which types of names describe the objects they can carry). In processes, polymorphism is expressed as explicit type parameters in input/output prefixes: messages are composed of a type and values of that type, and so type variables are relevant at the level of messages. Sangiorgi and Pierce [63] proposed a behavioral theory for Turner’s framework. Neither of these works address termination of well-typed processes nor studies relational parametricity. Building on [63], Jeffrey and Rathke [45] show that weak bisimulation is fully abstract for observational equivalence for an asynchronous polymorphic π-calculus with name equality testing. Berger et al. [10, 11] proposed a polymorphic π-calculus with both universal and existential quantification. The type system considered in [10, 11] is very different from ours, relying on a combination of linearity, so-called action types, and duality principles.
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A universal session type for untyped asynchronous communication

A universal session type for untyped asynchronous communication

defines the protocol of how to interact with a provider of a queue data structure that contains elements of some variable type A. In a session-typed interpretation of intuitionistic linear logic, session types are expressed from the point of view of the providing process, with the channel along which the process provides the session behavior being defined by the session type. This choice avoids the explicit dualization of a session type present in the original presentations of session types [20, 22] and those based on classical linear logic [42]. We adopt an equi-recursive [11] interpretation for recursive session types, silently equating a recursive session type with its unfolding and requiring types to be contractive [16].
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The cognitive-affective-conative model of destination image: A confirmatory analysis

The cognitive-affective-conative model of destination image: A confirmatory analysis

The rapid spread of social network through social media has been a new paradigm of society and culture as a result of development and convergence of IT and multimedia. Businesses today need to build up its brand identity with a different way from the past, communicating with its customers through SNS. This study aims to investigate SNS as a communication channel to form brand identity which is a crucial factor of a brand, and emphasize the role for the enlargement of brand equity value. Also, it discovers the differences of influence depending on the types of SNS and the degree of commitment. The implications of this study are as follows. First, it gives late starters the positive possibility to utilize SNS as a branding management method by analyzing the brand identity appearing on SNS of the brand utilizing social media. Second, it suggests that it is more effective to choose SNS which is suitable for its purpose considering qualitative relationship with customers, not quantitative unconditionally
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Relationship between Holocene climate variations over southern Greenland and eastern Baffin Island and synoptic circulation pattern

Relationship between Holocene climate variations over southern Greenland and eastern Baffin Island and synoptic circulation pattern

types for Akvaqiak Lake, 17 pollen types for Qipisarqo Lake, 15 dinocyst types for core HU021 and 17 dinocyst types for core HU085.. For PCA, as for the quantitative.[r]

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J. Soc. Bras. Fonoaudiol.  vol.24 número1 en v24n1a15

J. Soc. Bras. Fonoaudiol. vol.24 número1 en v24n1a15

The aim of the present study was to characterize the phonological awareness abilities of a child with Acquired Immunodeficiency Syndrome (AIDS) before and after speech-language therapy. The participant was a 6-year- -old girl, first-grade Elementary School student, with AIDS acquired by vertical transmission. The child’s phonological awareness abilities were evaluated using the Instrument of Sequential Evaluation of Phonological Awareness (CONFIAS). After this first evaluation, a closed therapeutic program (15 sessions) for phonolo- gical awareness was developed, consisting of activities for syllabic and phonemic levels. The CONFIAS was reapplied in the last session in order to investigate therapy effectiveness. In the pre-therapy assessment, the child scored 18 points in syllable tasks and 1 point in phoneme tasks, with a total score of 19 points. In the post-therapy assessment, the child scored 26 points in syllable tasks and 11 points in phoneme tasks, with a total score of 37 points. This study allowed us to characterize the performance of a child with AIDS in tasks of phonological awareness and the effectiveness of the therapeutic program. The score obtained before therapy was much lower than expected for the child’s age, and presented significant improvement after speech-language therapy. Thus, professionals working with this population must be aware of therapeutic programs that approach phonological processing abilities in addition to other aspects.
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Provisional summary record of the closing session

Provisional summary record of the closing session

El Presidente declara clausurada la XXXII Reuni6n del Consejo Directivo de la Organizaci6n Panamericana de la Salud,. XXXIX Reuni6n del Comite Regional de la Organizaci6n[r]

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Provisional summary records : plenary session 1-7

Provisional summary records : plenary session 1-7

Item _ 3: Representation of the Executive Committee at the XXX Meeting of the Directing Council of PAHO, XXXVI Meeting of the Regional Committee of WHO for the Americas.. Tema 3: Represe[r]

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Convergent types for shared memory

Convergent types for shared memory

As the number of cores increases in a multi-core system, the synchronization cost becomes more apparent favouring the relaxation of concurrent object semantics for scaling the pro- grams [ 34 ]. Programming patterns that attempt to limit the associated cost of the required synchronization on the memory accesses are emerging. As in CRDTs, the concept of merge- able data types is widely in use on distributed systems. Each replica can be concurrently updated, and later be merged with other replicas, while it is guaranteed that all nodes reach a convergent state once all updates have been delivered. Although, high latency network and possible reordering of messages in distributed systems, resulted in properties much different from what is required in shared memory systems. It is relatively simple to recog- nize that the use of such data types could be adapted, with enhanced and specific settings, to perform on a shared memory environment.
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A Novel Semantically-Time-Referrer based Approach of Web Usage Mining for Improved Sessionization in Pre-Processing of Web Log

A Novel Semantically-Time-Referrer based Approach of Web Usage Mining for Improved Sessionization in Pre-Processing of Web Log

1) Time Oriented Session Identification: Time oriented session identification method is a traditional method which considers temporal boundaries such as a maximum session length which is normally taken as 30 minutes or the maximum time allowable for each page view, which is normally taken as 10 minutes. There are several other ways to calculate the time asdiscussed in related work. The exemplary explanation of time heuristic is shown in Table 4. According to this method, whenever the stay time (10min) or complete session time (30min) gets greater than the threshold value, it has created new session. In third and sixth row the time gap becomes more then 10 minutes, due to this new session S2 and S3 are created, whereas if we consider the navigation path, the session should remain same. Therefore, this is the biggest limitation of this method as most of the time one session is divided in to more than one session or many sessions comes into one session. Table 5 shows the results of Time-heuristic sessionization for three different log files which has been taken as input. Results are discussed in the section of results and discussion.
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Ten simple rules for chairing a scientific session.

Ten simple rules for chairing a scientific session.

ed. It is your job to excite people at the session and have them stay in the auditorium. Regarding the speakers, in- troduce each one before they begin, providing their background and highlight- ing their major accomplishments. Speak- ers love to be properly introduced and the audience likes to feel they know the person speaking. But for the sake of both the timing of the session and your speakers, do keep it brief. Are you expected to give any housekeeping messages or to remind people to switch off their phones? Allow time for that if so.

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Session 2 – Compositions with Game Technology

Session 2 – Compositions with Game Technology

Ben Jameson: ‘ Construction in Metal: Investigating Authenticity in Musical Performance Using Video Game Peripherals ’.. Beth Carroll: ‘ Raw Data: Interactive Musical Interplay and Sou[r]

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UNIVERSIDADE FEDERAL DE UBERLÂNDIA PROGRAMA DE PÓS-GRADUAÇÃO EM CIÊNCIAS DA SAÚDE FACULDADE DE MEDICINA LARISSA APARECIDA SANTOS MATIAS

UNIVERSIDADE FEDERAL DE UBERLÂNDIA PROGRAMA DE PÓS-GRADUAÇÃO EM CIÊNCIAS DA SAÚDE FACULDADE DE MEDICINA LARISSA APARECIDA SANTOS MATIAS

Introduction: Hypertension has a higher prevalence in postmenopausal women, and physical exercise has been considered an important alternative means of treatment and prevention of this disease. Purpose: Verify acute and chronic responses to ambulatory blood pressure after combined aerobic and resisted exercises. Methods: Participants were 14 postmenopausal women taking medicated hypertensives (58.8±1.0 years of age, weighing 27.7±1.2 kg/m² and 7.2±1.5 years post menopause) and were submitted to an acute session and to training for ten weeks with combined exercise. This consisted of thirty sessions lasting 45 minutes, 5 minutes of warm-up, 20 minutes of aerobic exercise on the treadmill and 20 minutes of resisted exercise. Blood pressure was assessed at rest and for 24 hours by ambulatory blood pressure monitoring (ABPM). ABPM was performed on three occasions: pre-training at rest (Baseline), after an acute exercise session (Acute) and rest after training (Chronic). From the ABPM data, blood pressure variability (BPV) and the area under the curve (AUC) of blood pressure were calculated. Results: Statistical analysis showed that the AUC of systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean blood pressure (MBP) for the Chronic measurement was smaller than the Baseline measurement, but there was no difference between the Acute and Baseline measurements. The BPV of SBP, DBP and MBP was reduced for the Acute measurement in relation to Baseline, but there was no difference between the Chronic and Baseline measurements. Conclusion: Combined exercise reduces chronic ambulatory blood pressure, but not does after a single acute session. In contrast, BPV decreases after a single acute session, but does not change chronically.
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QoS mapping and adaptation in next generation networks eve  QoS

QoS mapping and adaptation in next generation networks eve QoS

To allow the distribution of multi-user sessions throughout heterogeneous networks the mapping of sessions-flows quality level requirements into the most suitable network service class seems to be mandatory. Moreover, the QoS mapping scheme should be independent of the QoS model and transport technology supported by each network and between them. Furthermore, in order to increase the level of user satisfaction, it is required to keep the on-going multi- user sessions with acceptable quality level, independently of the users’ movement. However, when the QoS mapping control can not ensure the QoS committed for each session-flow, for instance due to the attachment of users to a congested access network, a QoS adaptation mechanism is required to adapt the session-flows to the network conditions. The adaptation mechanism aims to decrease the level of QoS degradation in the session by dropping or adding low priority session-flows, requesting the mapping of some session-flows to a different network class, or by requesting the adjustment of the network resources allocated to some network classes.
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Enhancing smart grid with sessionoriented communication system to truly support reliability and robustness

Enhancing smart grid with sessionoriented communication system to truly support reliability and robustness

The SAC allows seamless interactions and organiza- tion of the different elements inside and outside the Smart Grid system. The main idea is to make transparent the heterogeneity aspects of the overall Smart Grid sys- tem, in terms of technology, location, naming, addressing, etc. The mapping between interfaces and component discovering are done by SAC, which self-organizes the system to keep available IED information coherent. Therefore, whenever a Smart Grid application intends subscribing IEDs, it simply triggers SAC in local system providing the intended measures and Smart Grid sub-system (e.g., substation). Based on that information, SAC retrieves in local book tables the IEDs identifiers, composes the QoS-requirements of the session (based on static information or policies) and requests establishing the demanding session.
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Psychol. Neurosci.  vol.4 número2

Psychol. Neurosci. vol.4 número2

Using a Stroop matching task, we evaluated how alcohol affects the time needed to overcome Stroop conlict and whether practice might reverse the effect of alcohol. Participants (n = 16) performed two sessions in which they had to compare the color of a color-word with the meaning of a color-word in neutral color. The two task stimuli were presented simultaneously or with a Stimulus Onset Asynchrony (SOA) of 200, 500, or 800 ms. For half of the subjects, alcohol was administered in the irst session, and for the other half, alcohol was administered in the second session. The results showed that the Stroop effect was signiicant at the 0 and 200 ms intervals in the sober subjects. Moreover, in untrained intoxicated individuals, interference endured until the 500 ms interval, a result that was abolished in trained intoxicated subjects. In conclusion, alcohol increased the time needed for Stroop matching task conlict resolution. However, this deleterious effect was minimized by a previous practice session. Keywords: alcohol, feature-attention, practice, Stroop task, reaction time.
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Action and valence modulate choice and choice-induced preference change.

Action and valence modulate choice and choice-induced preference change.

Fig 2. Results. a. The Rating change between the two sessions is displayed for the eight conditions (resulting from the factors Session 1 Choice/Session 2 Choice, Chosen/Unchosen, Go/No Go) in the positive and negative valence group. There was an effect of Choice (chosen larger than unchosen), that was stronger in the experimental condition (larger in Session 1 Choice than Session 2 Choice). In the positive valence group choosing a picture by action led to increased positive choice-induced preference change (defined as the interaction term of Choice and Condition, see Fig. 2b). This effect was absent in the negative valence group. Note that the overall interaction effect is driven by differences across all conditions, including the Session 2 Choice condition. b. To illustrate the overall interaction, the choice-induced preference change (interaction term of Condition (Session 1 Choice/Session 2 Choice) and Choice (Chosen/Unchosen)) is displayed for choice made by action and inaction in both groups, resulting in four conditions (Choice by action in the positive valence group; Choice by inaction in the positive valence group; Choice by action in the negative valence group; Choice by inaction in the negative valence group). Error bars represent the standard error of the mean.
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