Behavioural Equivalence Research Articles

Comparison of dissolution profiles of brand name and generic drugs of mycophenolate mofetil in the presence of concomitant drugs

Generic drugs have become popular because they reduce medical costs. However, switching from a brand name drug to a generic drug of mycophenolate mofetil (MMF) in immunosuppressive therapy after kidney transplantation resulted in an insufficient increase in its blood concentration in some cases. Immunosuppressive therapy after transplantation typically involves a multidrug strategy. Therefore, changes in efficacy due to switching to a generic drug of MMF may be due to its combination with other drugs. Since the first barrier to the absorption of an orally administered formulation is dissolution, the present study examined the effects of prednisolone (PDN) and tacrolimus (TAC), which are used in immunosuppressive therapy, on the dissolution behavior of MMF. A dissolution experiment was performed in the 1st liquid for dissolution testing (pH 1.2), McIlvaine buffer (pH 4.0), and a 2nd liquid for dissolution testing (pH 6.8) under the single condition of the brand name drug and two generic drugs of MMF as well as under combined conditions with PDN and TAC. Although the initial dissolution rate of MMF differed between the brand name and generic drugs, no significant difference was observed in the final dissolution rate. Furthermore, the f2 value, which evaluates the equivalence of dissolution behavior, was within the standard range. In the 2nd liquid for dissolution testing (pH 6.8), the dissolution rate and ratio slightly decreased under the combined condition with PDN or TAC; however, in comparisons with the single conditions, the f2 value was within the standard range. Therefore, a reduced blood concentration due to switching to a generic drug of MMF may not be due to a change in dissolution behavior.

Systems of fixpoint equations: Abstraction, games, up-to techniques and local algorithms

Systems of fixpoint equations over complete lattices, consisting of (mixed) least and greatest fixpoint equations, allow one to express many verification tasks such as model-checking of various kinds of specification logics or the check of coinductive behavioural equivalences. In this paper we develop a theory of approximation for systems of fixpoint equations in the style of abstract interpretation: a system over some concrete domain is abstracted to a system in a suitable abstract domain, with conditions ensuring that the abstract solution represents a sound/complete overapproximation of the concrete solution. Interestingly, up-to techniques, a classical approach used in coinductive settings to obtain easier or feasible proofs, can be interpreted as abstractions in a way that they naturally fit into our framework and extend to systems of equations. Additionally, relying on the approximation theory, we can characterise the solution of systems of fixpoint equations over complete lattices in terms of a suitable parity game, generalising some recent work that was restricted to continuous lattices. The game view opens the way for the development of local algorithms for characterising the solution of such equation systems. We describe a local algorithm for checking the winner on specific game positions. This corresponds to answering the associated verification question (i.e., for model checking, whether a state satisfies a formula or, for equivalence checking, whether two states are behaviourally equivalent). The algorithm can be combined with abstraction and up-to techniques, thus providing ways of speeding up the computation.

Relating behaviour of data-aware process models

Data Petri nets (DPNs) have gained traction as a model for data-aware processes, thanks to their ability to balance simplicity with expressiveness, and because they can be automatically discovered from event logs. While model checking techniques for DPNs have been studied, more complex analysis tasks that are highly relevant for BPM are beyond methods known in the literature. We focus here on equivalence and inclusion of process behaviour with respect to language and configuration spaces, optionally taking data into account. Such comparisons are important in the context of key process mining tasks, namely process repair and discovery, and related to conformance checking. To solve these tasks, we propose approaches for bounded DPNs based on constraint graphs, which are faithful abstractions of the reachable state space. Though the considered verification tasks are undecidable in general, we show that our method is a decision procedure DPNs that admit a finite history set. This property guarantees that constraint graphs are finite and computable, and was shown to hold for large classes of DPNs that are mined automatically, and DPNs presented in the literature. The new techniques are implemented in the tool ada, and an evaluation proving feasibility is provided.

Triple equivalence of the oscillatory behavior for scalar delay differential equations

Triple equivalence of the oscillatory behavior for scalar delay differential equations

The Evolution Mechanism of Correctness for Cyber-Physical System

Cyber-physical Systems (CPS) are widely used in all areas of life. Ensuring the correctness of CPS remains an enduring challenge during its development and design phases. One approach to ascertain the correctness of CPS is behavior equivalence based on bisimulation. However, whether the implementation development process develops in the right direction has an important impact on obtaining the correct system implementation. Especially, the development process of complex CPS often yields a multitude of implementation versions, the correlation among these versions partly signifies the correctness of the development process. This paper formalizes the relationship between the implementation versions and establishes a formal description of the development process progressing in the correct direction, leveraging the concept of a “limit idea.” Initially, we introduce the concept of “limit bisimulation” for CPS systems to delineate implementations acquired during the CPS development process. Specific limit bisimulations are demonstrated to represent distinct scenarios within the development process. Subsequently, the convergence mechanism of implementations is modeled through bisimulation limits, encapsulating the CPS’s specification as the ultimate goal of obtained implementations during the development process. Finally, the congruence property of the bisimulation limit is proved, which accounts for the relation between specification and implementation versions can be decomposed into a refinement hierarchy. The limit theorem of bisimulation in CPS can help the designer and developer of CPS to comprehend the development course better.

Behavioral equivalences for AbU: Verifying security and safety in distributed IoT systems

Attribute-based memory Updates (▪in short) is an interaction mechanism recently introduced for adapting the Event-Condition-Action (ECA) programming paradigm to distributed reactive systems, such as autonomic and smart IoT device ensembles. In this model, an event (e.g., an input from a sensor, or a device state update) can trigger an ECA rule, whose execution can cause the state update of (possibly) many remote devices at once; the latter are selected “on the fly” by means of predicates over their state, without the need of a central coordinating entity.However, the combination of different ▪systems may yield unexpected interactions, e.g., when a new device is added to an existing secure system, potentially hindering the security of the whole ensemble of devices. This can be critical in the IoT, where smart devices are more and more pervasive in our daily life.In this paper, we consider the problem of ensuring security and safety requirements for ▪systems (and, in turn, for IoT devices). The first are a form of noninterference, as they correspond to avoid forbidden information flows (e.g., information flows violating confidentiality); while the second are a form of non-interaction, as they correspond to avoid unintended executions (e.g., leading to erroneous/unsafe states).In order to formally model these requirements, we introduce suitable behavioral equivalences for ▪. These equivalences are generalizations of hiding bisimilarity, i.e., a kind of weak bisimilarity where we can compare systems up to actions at different levels of security. Leveraging these behavioral equivalences, we propose (syntactic) sufficient conditions guaranteeing the requirements and, then, effective algorithms for statically verifying such conditions.

Anomalous heat transport and universality in macroscopic diffusion models

Anomalous diffusion is ubiquitous in nature and relevant for a wide range of applications, including energy transport, especially in bio- and nano-technologies. Numerous approaches have been developed to describe it from a microscopic point of view, and recently, it has been framed within universality classes, characterized by the behaviour of the moments and auto-correlation functions of the transported quantities. It is important to investigate whether such universality applies to macroscopic models. Here, the spectrum of the moments of the solutions of the transport equations is investigated for three continuous PDE models featuring anomalous diffusion. In particular, we consider the transport described by: (i) a generalized diffusion equation with time-dependent diffusion coefficient; (ii) the Porous Medium Equation and (iii) the Telegrapher Equation. For each model, the key features of the source-type solution as well as the analytical results for the moment analysis are revisited and extended via both analytical and numerical approaches. Equivalence of the asymptotic behaviour of the corresponding heat transport is confirmed within the realm of weak anomalous diffusion.

Quantum Bisimilarity via Barbs and Contexts: Curbing the Power of Non-deterministic Observers

Past years have seen the development of a few proposals for quantum extensions of process calculi. The rationale is clear: with the development of quantum communication protocols, there is a need to abstract and focus on the basic features of quantum concurrent systems, like CCS and CSP have done for their classical counterparts. So far, though, no accepted standard has emerged, neither for the syntax nor for the behavioural semantics. Indeed, the various proposals do not agree on what should be the observational properties of quantum values, and as a matter of fact, the soundness of such properties has never been validated against the prescriptions of quantum theory. To this aim, we introduce a new calculus, Linear Quantum CCS (lqCCS), and investigate the features of behavioural equivalences based on barbs and contexts. Our calculus can be thought of as an asynchronous, linear version of qCCS, which is in turn based on value-passing CCS. The combination of linearity and asynchronous communication fits well with the properties of quantum systems (e.g. the no-cloning theorem), since it ensures that each qubit is sent exactly once, precisely specifying which qubits of a process interact with the context. We exploit contexts to examine how bisimilarities relate to quantum theory. We show that the observational power of general contexts is incompatible with quantum theory: roughly, they can perform non-deterministic moves depending on quantum values without measuring (hence perturbing) them. Therefore, we refine the operational semantics in order to prevent contexts from performing unfeasible non-deterministic choices. This induces a coarser bisimilarity that better fits the quantum setting: (i) it lifts the indistinguishability of quantum states to the distributions of processes and, despite the additional constraints, (ii) it preserves the expressiveness of non-deterministic choices based on classical information. To the best of our knowledge, our semantics is the first one that satisfies the two properties above.

From Perugino to Picasso revisited: Electrophysiological responses to faces in paintings from different art styles

Behavioral research (Ventura, et al., 2023) suggested that pictorial representations of faces varying along a realism-distortion spectrum elicit holistic processing as natural faces. Whether holistic face neural responses are engaged similarly remains, however, underexplored. In the present study, we evaluated the neural correlates of naturalist and artistic face processing, by exploring electrophysiological responses to faces in photographs versus in four major painting styles. The N170 response to faces in photographs was indistinguishable from that elicited by faces in the renaissance art style (depicting the most realistic faces), whilst both categories elicited larger N170 than faces in other art styles (post-impressionism, expressionism, and cubism), with a gradation in brain activity. The present evidence suggest that visual processing may become finer grained the more the realistic nature of the face. Despite behavioral equivalence, the neural mechanisms for holistic processing of natural faces and faces in diverse art styles are not equivalent.

A model of actors and grey failures

Existing models for the analysis of concurrent processes tend to focus on fail-stop failures, where processes are either working or permanently stopped, and their state (working/stopped) is known. In fact, systems are often affected by grey failures: failures that are latent, possibly transient, and may affect the system in subtle ways that later lead to major issues (such as crashes, limited availability, overload). We introduce a model of actor-based systems with grey failures, based on two interlinked layers: an actor model, given as an asynchronous process calculus with discrete time, and a failure model that represents failure patterns to inject in the system. Our failure model captures not only fail-stop node and link failures, but also grey failures (e.g., partial, transient). We give a behavioural equivalence relation based on weak barbed bisimulation to compare systems on the basis of their ability to recover from failures, and on this basis we define some desirable properties of reliable systems. By doing so, we reduce the problem of checking reliability properties of systems to the problem of checking bisimulation.

Back to the format: A survey on SOS for probabilistic processes

In probabilistic process algebras the classic qualitative description of process behaviour is enriched with quantitative information on it, usually modelled in terms of probabilistic weights and/or distributions over the qualitative behaviour. In this setting, we use behavioural equivalences to check whether two processes show exactly the same behaviour, and, if this is not the case, we can use behavioural metrics to measure the distance between them. Compositional reasoning requires that equivalence, or closeness, of behaviour of two processes are not destroyed when language operators are applied on top of them in order to build larger processes. Formally, the equivalence must be a congruence, and the metric must be uniformly continuous, with respect to language operators. Instead of verifying these compositional properties by hand, operator-by-operator, it is much more convenient to prove them for a class of operators once for all, and to check that the operators one is dealing with are in that class. This is achieved by means of SOS specification formats: they consist in a set of syntactical constraints characterising a class of operators on the patterns of SOS rules, that define the operational semantics of languages. With this survey, we aim to collect and describe the specification formats that have been proposed in the literature to guarantee the compositional properties of (variants of) bisimulation equivalences and bisimulation metrics in the probabilistic setting.

Symbolic protocol verification with dice1

Symbolic protocol verification generally abstracts probabilities away, considering computations that succeed only with negligible probability, such as guessing random numbers or breaking an encryption scheme, as impossible. This abstraction, sometimes referred to as the perfect cryptography assumption, has shown very useful as it simplifies automation of the analysis. However, probabilities may also appear in the control flow where they are generally not negligible. In this paper we consider a framework for symbolic protocol analysis with a probabilistic choice operator: the probabilistic applied π-calculus. We define and explore the relationships between several behavioral equivalences. In particular we show the need for randomized schedulers and exhibit a counter-example to a result in a previous work that relied on non-randomized ones. As in other frameworks that mix both non-deterministic and probabilistic choices, schedulers may sometimes be unrealistically powerful. We therefore consider two subclasses of processes that avoid this problem. In particular, when considering purely non-deterministic protocols, as is done in classical symbolic verification, we show that a probabilistic adversary has – maybe surprisingly – a strictly superior distinguishing power for may testing, which, when the number of sessions is bounded, we show to coincide with purely possibilistic similarity.

Fuzzy Bisimulations for Nondeterministic Fuzzy Transition Systems

Bisimulations are established forms of behavioral equivalences for discrete event systems. Recently, bisimulations have been introduced to fuzzy transition systems (FTSs) and developed quickly. Relational lifting by using weight functions is one of the most used methods in bisimulation research, which lifts a crisp relation on the state spaces to a crisp relation on the distributions of state spaces of FTSs. This paper proposes a method, called fuzzy relational lifting method, via fuzzy similarity measures induced by residua (implications) in complete residuated lattices. In contrast with the existing method, fuzzy relational lifting method relaxes the conditions of lifting relation by using weight functions and is a generalization of the method. Some properties of fuzzy lifting operation are presented. Based on the fuzzy lifting operation, a fuzzy bisimulation for nondeterministic fuzzy transition systems (NFTSs) is introduced, which is much more natural and robust than some behavioral measures, and can measure the degree of similarity between any two states which are deemed to be equivalent intuitively but simply distinguished by other behavioral measures. Then some properties of fuzzy bisimulations are provided. Moreover, a fixedpoint characterization of fuzzy bisimulations is given and the greatest fuzzy bisimulation is computed. Finally, a real-valued logic is introduced to characterize fuzzy bisimulations over Godel algebra.

Gender dalam lokalitas budaya Panginyongan (Analisis strategi aktifis perempuan di Banyumas dalam mengelola konflik rumah tangga)

This article aims to find out how the locality value of panginyongan is implemented in Banyumasan culture, through a strategy for managing household role conflicts. The women activists who are active in public spaces, consciously have a dual role, but which factors are the most significant in supporting their harmony are not necessarily understood, so there has been no effort to maintain their existence. This article is a field study that takes a sample of women activists in Banyumas. The process of extracting data is carried out by means of in-depth interviews to determine the gender perception index, then using focus group discussions (FGD) to find out how the informants internalize the Panginyongan cultural values in their lives, especially related to the division of household roles. With the point of view of the subjects studied, the research is expected to produce a thick description of the strategy for managing household role conflicts through the cultural values of panginyongan. The results showed that the equality of positions had permeated through the equivalence of language, speech, attitude and behavior, so that none of the household players felt humiliated or exalted in filling domestic or public duties. If the wife is left for outdoor activities, the husband plays a role in completing the abandoned domestic work, and vice versa.

Studies on dissipative characteristics and equivalent model of particle damper in railway application

Particle damping technology brings the advantages of good durability, high reliability, insensitivity to temperature change and easy to be used in harsh environment. Hence, it has considerable potential for suppressing structural vibrations. In this study, a series of experiments under vertical harmonic excitations with different frequencies and acceleration amplitude were systematically conducted. The mechanical behavior and dissipative characteristics of the damper in railway application were analyzed by observing the particle motion state and calculating two energy dissipation evaluation indexes. The results show that the damping effect is strongly related to frequency and acceleration amplitude of the harmonic excitation. Subsequently, a discrete element model of the particle damper was established to simulate the test conditions, and the consistency between the simulation and test results verified the rationality of the simulation. The energy dissipation mechanism and characteristics of the particle damper were further explored based on the time-history responses of the contact force and energy dissipation. In order to simplify the analysis of nonlinear multi-particle damper, a simplified theoretical model consisting of mass, stiffness and damping elements was proposed based on the analysis of dynamic motion and dissipation mechanism. Based on the principle of energy equivalence and mechanical behavior equivalence between the theoretical model and simulation results, the equivalent equations were derived and the key parameters of the equivalent model were determined. These equivalent parameters are amplitude-frequency dependent. This model can be used to predict the damping properties of the damper at any input frequency or excitation amplitude, and to estimate the vibration attenuation performance of the damper for specific railway applications.

Up-to techniques for behavioural metrics via fibrations

AbstractUp-to techniques are a well-known method for enhancing coinductive proofs of behavioural equivalences. We introduce up-to techniques for behavioural metrics between systems modelled as coalgebras, and we provide abstract results to prove their soundness in a compositional way.In order to obtain a general framework, we need a systematic way to lift functors: we show that the Wasserstein lifting of a functor, introduced in a previous work, corresponds to a change of base in a fibrational sense. This observation enables us to reuse existing results about soundness of up-to techniques in a fibrational setting. We focus on the fibrations of predicates and relations valued in a quantale. To illustrate our approach, we provide an example on distances between regular languages.

Behavioural equivalences for continuous-time Markov processes

AbstractBisimulation is a concept that captures behavioural equivalence of states in a variety of types of transition systems. It has been widely studied in a discrete-time setting. The core of this work is to generalise the discrete-time picture to continuous time by providing a notion of behavioural equivalence for continuous-time Markov processes. In Chen et al. [(2019). Electronic Notes in Theoretical Computer Science347 45–63.], we proposed two equivalent definitions of bisimulation for continuous-time stochastic processes where the evolution is a flow through time: the first one as an equivalence relation and the second one as a cospan of morphisms. In Chen et al. [(2020). Electronic Notes in Theoretical Computer Science.], we developed the theory further: we introduced different concepts that correspond to different behavioural equivalences and compared them to bisimulation. In particular, we studied the relation between bisimulation and symmetry groups of the dynamics. We also provided a game interpretation for two of the behavioural equivalences. The present work unifies the cited conference presentations and gives detailed proofs.

THE ZHOU ORDINAL OF LABELLED MARKOV PROCESSES OVER SEPARABLE SPACES

AbstractThere exist two notions of equivalence of behavior between states of a Labelled Markov Process (LMP): state bisimilarity and event bisimilarity. The first one can be considered as an appropriate generalization to continuous spaces of Larsen and Skou’s probabilistic bisimilarity, whereas the second one is characterized by a natural logic. C. Zhou expressed state bisimilarity as the greatest fixed point of an operator $\mathcal {O}$ , and thus introduced an ordinal measure of the discrepancy between it and event bisimilarity. We call this ordinal the Zhou ordinal of $\mathbb {S}$ , $\mathfrak {Z}(\mathbb {S})$ . When $\mathfrak {Z}(\mathbb {S})=0$ , $\mathbb {S}$ satisfies the Hennessy–Milner property. The second author proved the existence of an LMP $\mathbb {S}$ with $\mathfrak {Z}(\mathbb {S}) \geq 1$ and Zhou showed that there are LMPs having an infinite Zhou ordinal. In this paper we show that there are LMPs $\mathbb {S}$ over separable metrizable spaces having arbitrary large countable $\mathfrak {Z}(\mathbb {S})$ and that it is consistent with the axioms of $\mathit {ZFC}$ that there is such a process with an uncountable Zhou ordinal.

Semantical Analysis of the Logic of Bunched Implications

We give a novel approach to proving soundness and completeness for a logic (henceforth: the object-logic) that bypasses truth-in-a-model to work directly with validity. Instead of working with specific worlds in specific models, we reason with eigenworlds (i.e., generic representatives of worlds) in an arbitrary model. This reasoning is captured by a sequent calculus for a meta-logic (in this case, first-order classical logic) expressive enough to capture the semantics of the object-logic. Essentially, one has a calculus of validity for the object-logic. The method proceeds through the perspective of reductive logic (as opposed to the more traditional paradigm of deductive logic), using the space of reductions as a medium for showing the behavioural equivalence of reduction in the sequent calculus for the object-logic and in the validity calculus. Rather than study the technique in general, we illustrate it for the logic of Bunched Implications (BI), thus IPL and MILL (without negation) are also treated. Intuitively, BI is the free combination of intuitionistic propositional logic and multiplicative intuitionistic linear logic, which renders its meta-theory is quite complex. The literature on BI contains many similar, but ultimately different, algebraic structures and satisfaction relations that either capture only fragments of the logic (albeit large ones) or have complex clauses for certain connectives (e.g., Beth’s clause for disjunction instead of Kripke’s). It is this complexity that motivates us to use BI as a case-study for this approach to semantics.

Nontransitive Preferences and Stochastic Rationalizability: A Behavioral Equivalence

Nontransitive Preferences and Stochastic Rationalizability: A Behavioral Equivalence