Reengineering the Corporation

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Computers And Intractability A Guide To The Theory Of Np Completeness

Even with the help of powerful metamodeling frameworks, the development of domain-specific graphical modeling tools is usually a complex, repetitive, and tedious task, which introduces substantial upfront costs often prohibiting such approaches in practice. In order to reduce these costs, the presented Cinco meta tooling suite is designed to provide a holistic approach that greatly simplifies the development of such domain-specific tools. Our solution is based on the idea to apply the concept of domain specialization also to the (meta-)domain of “domain-specific modeling tools”. Important here is our focus on complex graph-based models, comprising various kinds of nodes and edges together with their individual representation, correlations, and interpretation. This focus allows for high-level specifications of the model structures and functionalities as the prerequisite for push-button tool generation.

CINCO: a simplicity-driven approach to full generation of domain-specific graphical modeling tools

Over the last 50 years a wide variety of automatic network layout algorithms have been developed. Some are fast heuristic techniques suitable for networks with hundreds of thousands of nodes while others are multi-stage frameworks for higher-quality layout of smaller networks. However, despite decades of research currently no algorithm produces layout of comparable quality to that of a human. We give a new “human-centred” methodology for automatic network layout algorithm design that is intended to overcome this deficiency. User studies are first used to identify the aesthetic criteria algorithms should encode, then an algorithm is developed that is informed by these criteria and finally, a follow-up study evaluates the algorithm output. We have used this new methodology to develop an automatic orthogonal network layout method, HOLA, that achieves measurably better (by user study) layout than the best available orthogonal layout algorithm and which produces layouts of comparable quality to those produced by hand.

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HOLA: Human-like Orthogonal Network Layout

Automation of any business process primarily requires the identification of clear and precise requirements. However, the initially collected business requirements are usually expressed in natural language that creates ambiguities among different stakeholders. To overcome this problem, various business process modeling languages (BPMLs) have been introduced to represent the business requirements graphically. In this context, event-driven process chain (EPC) is a well-known BPML that supports the modeling and verification of business requirements in early automation phases. Although EPC is frequently researched to improve its modeling and verification capabilities, there is no study available yet to the best of our knowledge that examines and summarizes the latest EPC developments. Therefore, in this article, we comprehensively investigate the latest EPC approaches, trends, and tools for the modeling and verification of business requirements. Particularly, a systematic literature review is carried out to select and analyze 73 research studies published during 1998–2017. Consequently, the selected studies are classified into six categories, i.e., modeling (14), transformation (13), verification (17), general (20), semantics (5), and requirement (4). Moreover, latest EPC modeling approaches are identified and analyzed, i.e., UML (2), meta-model (3), integration (5), and EPC notations (4). Furthermore, EPC verification methods are also investigated, i.e., EPC (6), petri-nets (8), and other languages (3). Finally, 25 leading EPC tools have been presented, i.e., existing tools (14), proposed/developed tools, (5) and additional tools (6). It has been concluded that EPC provides adequate approaches and tool support for the modeling and verification of simple business requirements through atomic events. However, the complex business requirements cannot be modeled and verified through EPC due to the lack of complex event processing. Consequently, there is a strong need to include the support for the modeling and verification of complex events in EPC to manage multifaceted business requirements.

Event-Driven Process Chain for Modeling and Verification of Business Requirements–A Systematic Literature Review

We consider the problem of layering general directed graphs under height and possibly also width constraints. Given a directed graph \(G=(V,A)\) and a maximal height, we propose a layering approach that minimizes a weighted sum of the number of reversed arcs, the arc lengths, and the width of the drawing. We call this the Compact Generalized Layering Problem (CGLP). Here, the width of a drawing is defined as the maximum sum of the number of vertices placed on a layer and the number of dummy vertices caused by arcs traversing the layer. The CGLP is \(\mathcal {NP}\)-hard. We present two MIP models for this problem. The first one (EXT) is our extension of a natural formulation for directed acyclic graphs as suggested by Healy and Nikolov. The second one (CGL) is a new formulation based on partial orderings. Our computational experiments on two benchmark sets show that the CGL formulation can be solved much faster than EXT using standard commercial MIP solvers. Moreover, we suggest a variant of CGL, called MML, that can be seen as a heuristic approach. In our experiments, MML clearly improves on CGL in terms of running time while it does not considerably increase the average arc lengths and widths of the layouts although it solves a slightly different problem where the dummy vertices are not taken into account.

Compact Layered Drawings of General Directed Graphs

The Directed Layering Problem (DLP) solves a step of the widely used layer-based approach to automatically draw directed acyclic graphs. To cater for cyclic graphs, usually a preprocessing step is used that solves the Feedback Arc Set Problem (FASP) to make the graph acyclic before a layering is determined.

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A Generalization of the Directed Graph Layering Problem

The Directed Layering Problem (DLP) solves a step of the widely used layer-based approach to automatically draw directed acyclic graphs. To cater for cyclic graphs, usually a preprocessing step is used that solves the Feedback Arc Set Problem (FASP) to make the graph acyclic before a layering is determined. Here we present the Generalized Layering Problem (GLP), which solves the combination of DLP and FASP simultaneously, allowing general graphs as input. We present an integer programming model and a heuristic to solve the NP-complete GLP and perform thorough evaluations on different sets of graphs and with different implementations for the steps of the layer-based approach. We observe that GLP reduces the number of dummy nodes significantly, can produce more compact drawings, and improves on graphs where DLP yields poor aspect ratios.

We present a fundamentally different approach to orthogonal layout of data flow diagrams with ports. This is based on extending constrained stress majorization to cater for ports and flow layout. Because we are minimizing stress we are able to better display global structure, as measured by several criteria such as stress, edge-length variance, and aspect ratio. Compared to the layered approach, our layouts tend to exhibit symmetries, and eliminate inter-layer whitespace, making the diagrams more compact.

Ulf Rüegg

Papers

Compact Layered Drawings of General Directed Graphs

A Generalization of the Directed Graph Layering Problem

A Generalization of the Directed Graph Layering Problem

Stress-Minimizing Orthogonal Layout of Data Flow Diagrams with Ports

Stress-Minimizing Orthogonal Layout of Data Flow Diagrams with Ports