CPN Tools 4: Multi-formalism and Extensibility

Abstract. CPN Tools is an advanced tool for editing, simulating, and analyzing colored Petri nets. This paper discusses the fourth major re-lease of the tool, which makes it simple to use the tool for ordinary Petri nets, including adding inhibitor and reset arcs, and PNML export. This version also supports declarative modeling using constraints, and adds an extension framework making it easy for third parties to extend CPN Tools using Java.

Giant capacitance of a plane capacitor with a two-dimensional electron gas in a magnetic field

If a clean two-dimensional electron gas (2DEG) with small concentration $n$ comprises one (or both) electrodes of a plane capacitor, the resulting capacitance $C$ can be larger than the "geometric capacitance" $C_g$ determined by the physical separation $d$ between electrodes. A recent paper [1] argued that when the effective Bohr radius $a_B$ of the 2DEG satisfies $a_B << d$, one can achieve $C >> C_g$ at low concentration $nd^2 << 1$. Here we show that even for devices with $a_B > d$, including graphene, for which $a_B$ is effectively infinite, one also arrives at $C >> C_g$ at low electron concentration if there is a strong perpendicular magnetic field.Comment: 6 pages, 5 figures; updated discussion about bilayer systems; added discussion of fractional quantum Hall state

The role of cosmic rays and Alfven waves in the structure of the galactic halo

The effect that cosmic rays and the Alfven waves they generate have on the structure of the plasma distribution perpendicular to the galactic disk is examined. It is shown that the plasma distribution exhibits two length scales and the predicted values of gas density far from the galactic plane indicate that models involving hydrostatic equilibrium should be replaced by those allowing for a galactic wind

CPN Tools 4 : a process modeling tool combining declarative and imperative paradigms

CPN Tools is a tool for modeling, simulating, and analyzing colored Petri nets. The latest iteration of the tool, CPN Tools 4, extends this with constraints known from declarative languages such as Declare and DCR Graphs. Furthermore, this version introduces an explicit process perspective, powerful extensibility allowing third parties to extend the tools capabilities, and a visualization perspective making it possible to make high-level visualizations of executions directly in the tool. In our demonstration, we show how it is possible to create models incorporating declarative and imperative constructs and how to use these models to generate simulation logs that can be directly imported into ProM. We show o¿ the new process perspective on top of colored Petri nets, exemplify the use of the perspective to generate readable Java code directly from models, and show how the visualization perspective makes it possible to show the formal underlying model alongside an easier-to-grasp for non-experts high-level visualization. Our intended audience comprise current users of CPN Tools interested in recent developments and practitioners interested in colored Petri nets and hybrid models. We expect to tailor each demonstration to the wishes of the audience

Mixing Paradigms for More Comprehensible Models

Petri nets efficiently model both data- and control-flow. Control-flow is either modeled explicitly as flow of a specific kind of data, or implicit based on the data-flow. Explicit modeling of control-flow is useful for well-known and highly structured processes, but may make modeling of abstract features of models, or processes which are highly dynamic, overly complex. Declarative modeling, such as is supported by Declare and DCR graphs, focus on control-flow, but does not specify it explicitly; instead specifications come in the form of constraints on the order or appearance of tasks. In this paper we propose a combination of the two, using colored Petri nets instead of plain Petri nets to provide full data support. The combined approach makes it possible to add a focus on data to declarative languages, and to remove focus from the explicit control-flow from Petri nets for dynamic or abstract processes. In addition to enriching both procedural processes in the form of Petri nets and declarative processes, we also support a flow from modeling only abstract data- and control-flow of a model towards a more explicit control-flow model if so desired. We define our combined approach, and provide considerations necessary for enactment. Our approach has been implemented in CPN Tools 4

KeyValueSets : event logs revisited

In process mining, event logs have traditionally been considered as strictly hierarchical lists of events, where each event belongs to exactly one case, refers to exactly one activity and has a timestamp. Based on this assumption, the XES standard has been developed to describe event logs. In this paper, we reconsider the notion of an event log, by focussing on events as the primary entity. Furthermore, we do not assume the presence of traditional notions like cases and timestamps (or even ordering), but we introduce mappings for sorting and grouping our KeyValueSets. This allows us to provide a generic transformation from a wide variety of formats to standard XES logs

UnconstrainedMiner : efficient discovery of generalized declarative process models

Process discovery techniques derive a process model from observed behavior (e.g., event logs). In case of less structured processes, declarative models have notable advantages over procedural models. A declarative model consists of a set of temporal constraints over the activities in the event log. In this paper, we address three limitations of current discovery techniques: their unclear semantics of declarative constraints for business processes, their non-performative discovery of constraints, and their potential identification of vacuous constraints. We implemented our contributions as a declarative discovery algorithm for the Declare language. Our evaluations on a real-life event log indicate that it outperforms state of the art techniques by several orders of magnitude

PRM51 From Clinical Trial to Real-World Evidence: A Systematic Approach to Identifying Data Sources for Observational Research

Edifici industrial de dos cossos de planta baixa i tres plantes pis acabades amb mansarda. Destaca el nombre i dimensions de les obertures que permeten una gran entrada de llum a l'interior i l'amplitud de les plantes diàfanes.Digitalitzat per Tecnodo