Tijs Slaats

• PhD Computer Science
• Professor (Assistant) at University of Copenhagen

In asylum decision-making, algorithmic tools are developed to optimize decision-making processes, for example, to streamline the application process. Accuracy, defined as correctly categorizing cases against a ground truth dataset, is a main concern. Data scientists employ outlier detection algorithms (ODA) to boost accuracy by fine-tuning datasets...

Smart contracts executed on blockchains are interactive programs where external actors generate events that trigger function invocations. Events can be emitted by participants asynchronously. However, some functionalities should be restricted to participants inhabiting specific roles in the system, which might be dynamically adjusted while the syst...

Vote-based blockchains construct a state machine replication (SMR) system among participating nodes, using Byzantine Fault Tolerance (BFT) consensus protocols to transition from one state to another. Currently, they rely on either synchronous or partially synchronous networks with leader-based coordination or costly Asynchronous Common Subset (ACS)...

Dynamic Condition Response (DCR) Graphs is a popular declarative process modelling notation which is supported by commercial modelling tools and has seen significant industrial adoption. The problem of aligning traces with DCR Graphs, with it’s multitude of applications such as conformance checking and log repair, has surprisingly not been solved y...

Choreographic models express coordination between business roles, in contrast to standard process models that merge local control flow and communication between parties. A choreography is realizable, also known as endpoint projectable, if the independent behaviour of each role in composition with other roles, only behaves exactly in the same way as...

We provide a practical translation from the Dynamic Condition Response (DCR) process modelling language to the Transaction Execution Approval Language (TEAL) used by the Algorand blockchain. Compared to earlier implementations of business process notations on blockchains, particularly Ethereum, the present implementation is four orders of magnitude...

Asylum is a legal protection granted by a state to individuals who demonstrate a well-founded fear of persecution or who face real risk of being subjected to torture in their country. However, asylum adjudication often depends on the decision maker’s subjective assessment of the applicant’s credibility. To investigate potential sources of bias in a...

We present a transformation of the Dynamic Condition Response (DCR) graph constraint based process specification language to safe Petri Nets with inhibitor and read arcs, generalized with an acceptance criteria enabling the specification of the union of regular and \(\omega \)-regular languages. We prove that the DCR graph and the resulting Petri N...

Asylum is a legal protection granted by a state to individuals who demonstrate a well-founded fear of persecution or who face real risk of being subjected to torture in their country. However, asylum adjudication often depends on the decision maker's subjective assessment of the applicant's credibility. To investigate potential sources of bias in a...

Individuals who demonstrate well-founded fears of persecution or face real risk of being subjected to torture, are eligible for asylum under Danish law. Decision outcomes, however, are often influenced by the subjective perceptions of the asylum applicant’s credibility. Literature reports on correlations between asylum outcomes and various extra-le...

It may be tempting for researchers to stick to incremental extensions of their current work to plan future research activities. Yet there is also merit in realizing the grand challenges in one’s field. This paper presents an overview of the nine major research problems for the Business Process Management discipline. These challenges have been colle...

We present a method and prototype tool supporting participatory mapping of domain activities to event data recorded in information systems via the system interfaces. The aim is to facilitate responsible secondary use of event data recorded in information systems, such as process mining and the construction of predictive AI models. Another identifie...

As refugee law practice enters the world of data, it is time to take stock as to what refugee law research can gain from technological developments. This article provides an outline for a computationally driven research agenda to tackle refugee status determination variations as a recalcitrant puzzle of refugee law. It firstly outlines how the grow...

Blockchain sharding splits a blockchain into several shards where consensus is reached at the shard level rather than over the entire blockchain. It improves transaction throughput and reduces the computational resources required of individual nodes. But a derivation of trustworthy consensus within a shard becomes an issue as the longest-chain base...

In this paper, we report the results of an exploratory study into the efficacy of noise filtering in improving the accuracy of declarative process mining. We apply the double-granularity mixed-dependency filtering algorithm as introduced by [9], to the DisCoveR declarative miner [1], and parameter optimise it to only perform coarse-grained filterin...

As refugee law practice enters the world of data, it is time to take stock as to what refugee law research can gain from technological developments. This article provides an outline for a computationally driven research agenda to tackle refugee status determination variations as a recalcitrant puzzle of refugee law. It first outlines how the growin...

We provide a practical translation from the Dynamic Condition Response (DCR) process modelling language to the Transaction Execution Approval Language (TEAL) used by the Algorand blockchain. Compared to earlier implementations of business process notations on blockchains, particularly Ethereum, the present implementation is four orders of magnitude...

This paper presents a method to manage private data stored on a blockchain. With our method, the blockchain’s features for log transparency and tamper-resistance are maintained, even though the data is only available to authorized users. The most relevant work so far randomly selects nodes to store the decryption key shares of a threshold cryptosys...

Declarative process modeling formalisms—which capture high-level process constraints—have seen growing interest, especially for modeling flexible processes. This paper presents DisCoveR, an efficient and accurate declarative miner for learning Dynamic Condition Response (DCR) Graphs from event logs. We present a precise formalization of the algorit...

We provide a formal semantics for timed DCR graphs with decision events and data, and show how the model supports merging declarative decision modelling and process modelling in one notation. We exemplify the model by an expense report process and discuss how decisions may be presented using DMN jointly with the DCR process notation. If data domain...

Process design artifacts have been increasingly used to guide the modeling of business processes. To support users in designing and understanding process models, different process artifacts have been combined in several ways leading to the emergence of the so-called “hybrid process artifacts”. While many hybrid artifacts have been proposed in the l...

This paper addresses the open technical problems of evolving executable, event-based process models by refinement, that is, by iteratively expanding a model until it has the required level of detail. Such iterative development is helpful because of the expectation that the next-step model is semantically compatible with the previous one, only with...

Contemporary process discovery methods take as inputs only positive examples of process executions, and so they are one-class classification algorithms. However, we have found negative examples to also be available in industry, hence we propose to treat process discovery as a binary classification problem. This approach opens the door to many well-...

Business processes, data, and run-time control state are all key elements in the design of enterprise applications. However, the different layers for processes, data, and control are usually represented using different technologies that must be explicitly combined and kept in sync. We introduce ReGraDa, a process definition and programming language...

In this paper, we take technical and practical steps towards the modularisation of compliant-by-design executable declarative process models. First, we demonstrate by example how the specific language of timed DCR graphs is capable of modelling complex legislation, with examples from laws regulating the functioning of local governments in Denmark....

Process models provide a blueprint for process execution and an indispensable tool for process management. Bearing in mind their trending use for requirement elicitation, communication and improvement of business processes, the need for understandable process models becomes a must. In this paper, we propose a research model to investigate the impac...

Imperative process models have become immensely popular. However, their use is usually limited to rigid and repetitive processes. Considering the inherent flexibility in most processes in the real-world and the increased need for managing knowledge-intensive processes, the adoption of declarative languages becomes more pertinent than ever. While th...

We study blockchain-based integrity-protected smart contracts as an implementation mechanism for municipal government processes. To this end, we attempted a prototype implementation of such a process in collaboration with a Danish Municipality. We find that such an implementation is possible, despite the obvious confidentiality requirements, and th...

Process modeling plays a central role in the development of today’s process-aware information systems both on the management level (e.g., providing input for requirements elicitation and fostering communication) and on the enactment level (providing a blue-print for process execution and enabling simulation). The literature comprises a variety of p...

Declarative process modeling formalisms - which capture high-level process constraints - have seen growing interest, especially for modeling flexible processes. This paper presents DisCoveR, an extremely efficient and accurate declarative miner for learning Dynamic Condition Response (DCR) Graphs from event logs. We precisely formalize the algorith...

Legal compliance is an important part of certifying the correct behaviour of a business process. To be compliant, organizations might hard-wire regulations into processes, limiting the discretion that workers have when choosing what activities should be executed in a case. Worse, hard-wired compliant processes are difficult to change when laws chan...

Knowledge-intensive processes, such as those encountered in health care, finance and government, tend to allow a large degree of flexibility: there are many possible solutions towards a goal, and it is left to the expertise of knowledge workers to find the one most suitable for the particular case at hand. As a result, such processes usually exhibi...

Process modeling aims at providing an external representation of a business process in the shape of a process model. The complexity of the modeling language, the usability of the modeling tool, and the expertise of the modeler are among the key factors defining the difficulty of a modeling task. Following a qualitative analysis approach, this work...

Hybrid modeling approaches have been proposed to represent processes that have both strictly regulated parts and loosely regulated parts. Such process is so-called Knowledge-intensive Process (KiP), which is a sequence of activities based on intense knowledge use and acquisition. Due to these very particular characteristics, the first author previo...

Process mining algorithms fall in two classes: imperative miners output flow diagrams, showing all possible paths, whereas declarative miners output constraints, showing the rules governing a process. But given a log, how do we know which of the two to apply? Assuming that logs exhibiting a large degree of variability are more suited for declarativ...

Declarative process discovery is the art of using historical data to better understand the responsibilities of an organisation: its governing business rules and goals. These rules and goals can be described using declarative process notations, such as Dynamic Condition Response (DCR) Graphs, which has seen widespread industrial adoption within Denm...

Process design artifacts (e.g., process models, textual process descriptions and simulations) are increasingly used to provide input for requirements elicitation and to facilitate the design of business processes. To support the understandability of process models and make them accessible for end-users with different backgrounds, several hybrid rep...

We provide the first formal model for declarative choreographies, which is able to express general omega-regular liveness properties. We use the Dynamic Condition Response (DCR) graphs notation for both choreographies and end-points. We define end-point projection as a restriction of DCR graphs and derive the condition for end-point projectability...

The EcoKnow project strives to promote flexible case management systems in the public administration and empower end-users (i.e., case workers) to make sense of digitized models of the law. For this, a hybrid representation combining the declarative DCR notation with textual annotations depicting the law text and a simulation tool to simulate the e...

Process modelling notations fall in two broad categories: declarative notations, which specify the rules governing a process; and imperative notations, which specify the flows admitted by a process. We outline an empirical approach to addressing the question of whether certain process logs are better suited for mining to imperative than declarative...

We explore the complexity of reachability and run-time refinement under safety and liveness constraints in event-based process models. Our study is framed in the DCR\(^\star \) process language, which supports modular specification through a compositional operational semantics. DCR\(^\star \) encompasses the “Dynamic Condition Response (DCR) graphs...

In this paper, we present a technique for the discovery of hybrid process models that combine imperative and declarative constructs. In particular, we first employ the popular Inductive Miner to generate a fully imperative model from a log. Like most imperative miners, the Inductive Miner tends to return so-called flower models for the less structu...

(Note that we have updated the paper to the accepted version on 23 Jan 2018) Blockchain technology offers a sizable promise to rethink the way inter-organizational business processes are managed because of its potential to realize execution with- out a central party serving as a single point of trust (and failure). To stimulate research on this pro...

Situation faced: Exformatics, a Danish adaptive case-management vendor, wanted to leverage declarative process tools to support the flexible processes found at BRFkredit. However, switching from the more common flow-based notations to a declarative notation brought new challenges in terms of understandability. We undertook the project described in...

Blockchain technology promises a sizable potential for executing inter-organizational business processes without requiring a central party serving as a single point of trust (and failure). This paper analyzes its impact on business process management (BPM). We structure the discussion using two BPM frameworks, namely the six BPM core capabilities a...

In the area of business process modelling, declarative notations have been proposed as alternatives to notations that follow the dominant, imperative paradigm. Yet, the choice between an imperative or declarative style of modelling is not always easy to make. Instead, a mixture of these styles is sometimes preferable. This observation has underpinn...

Case Management (CM) is a BPM technology for supporting flexible services orchestration. CM approaches like CMMN, an OMG standard, and GSM, one of CMMN’s core influences, use Event-Condition-Action rules, which can be inconsistent due to cyclic inter-dependencies between the rules; repairing such an inconsistent case management schema is difficult....

Modern form-based end-user interfaces are highly variable and need to adapt to the choices made by the user. To describe such adaptations programmatically is time and resource intensive and therefore more generic approaches are preferable. Form-based UIs are often very flexible: one usually has a large degree of freedom in the order in which fields...

As a provider of Electronic Case Management solutions to knowledge-intensive businesses and organizations, the Danish company Exformatics has in recent years identified a need for flexible process support in the tools that we provide to our customers. We have addressed this need by adapting DCR Graphs, a formal declarative workflow notation develop...

Declarative or constraint-based business process and workflow notations, in particular DECLARE and Dynamic Condition Response (DCR) graphs, have received increasing interest in the last decade as possible means of addressing the challenge of supporting at the same time flexibility in execution, adaptability and compliance. However, the definition o...

We study modularity, run-time adaptation and refinement under safety and liveness constraints in event-based process models with dynamic sub-process instantiation. The study is part of a larger programme to provide semantically well-founded technologies for modelling, implementation and verification of flexible, run-time adaptable processaware info...

We present a new declarative model with composition and hierarchical definition of processes, featuring (a) incremental refinement, (b) adaptation of processes, and (c) dynamic creation of sub-processes. The approach is motivated and exemplified by a recent case manage-ment solution delivered by our industry partner Exformatics A/S. The approach is...

The declarative-procedural dichotomy is highly relevant when choos-ing the most suitable process modeling language to represent a discovered pro-cess. Less-structured processes with a high level of variability can be described in a more compact way using a declarative language. By contrast, procedural pro-cess modeling languages seem more suitable...

We report on a recent industrial project carried out by Exformatics A/S in which the company used the declarative DCR Graphs notation to model and implement the grant application process of a Danish foundation. We present the process and discuss the advantages of the approach and challenges faced both while modelling and implementing the process. F...

We present the first session typing system guaranteeing request-response liveness properties for possibly non-terminating communicating processes. The types augment the branch and select types of the standard binary session types with a set of required responses, indicating that whenever a particular label is selected, a set of other labels, its re...

We describe how the declarative Dynamic Condition Response (DCR) Graphs process model can be used for trustworthy adaptive case management by leveraging the flexible execution, dynamic composition and adaptation supported by DCR Graphs. The dynamically composed and adapted graphs are verified for deadlock freedom and liveness in the SPIN model chec...

Declarative workflow languages have been a growing research subject over the past ten years, but applications of the declarative approach in industry are still uncommon. Over the past two years Exformatics A/S, a Danish provider of Electronic Case Management systems, has been cooperating with researchers at IT University of Copenhagen (ITU) to crea...

Declarative modeling has attracted much attention over the last years, resulting in the development of several academic declarative modeling techniques and tools. The absence of empirical evaluations on their use and usefulness, however, raises the question whether practitioners are attracted to using those techniques. In this paper, we present a s...

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 dy...

We conservatively extend the declarative Dynamic Condition Response (DCR) Graph process model, introduced in the PhD thesis of the second author, to allow for discrete time deadlines. We prove that safety and liveness properties can be verified by mapping finite timed DCR Graphs to finite state transition systems. We exemplify how deadlines can int...

We propose the recently introduced declarative and event-based Dynamic Condition Response (DCR) Graphs process model as a formal basis for modular implementation of context-sensitive and aspect-oriented processes. The proposal is supported by a new join operator allowing modular composition and refinement of DCR Graphs. We give small illustrative e...

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 th...

We give a general technique for safe distribution of a declarative (global) process as a network of (local) synchronously communicating declarative processes. Both the global and local processes are given as Dynamic Condition Response (DCR) Graphs. DCR Graphs is a recently introduced declarative process model generalizing labelled prime event struc...

We present a formal technique for safe distribution of workflow processes described declaratively as nested Dynamic Condition Response (DCR) Graphs and apply the technique to a distributed healthcare workflow. Concretely, we provide a method to synthesize from a nested DCR Graph and any distribution of its atomic events a set of local process graph...

We present a case study of the use of Dynamic Con- dition Response (DCR) Graphs, a recently introduced declarative business process model, in the design of a cross-organizational case management system being developed by Exformatics A/S, a Danish provider of knowledge and workflow management systems. We show how DCR Graphs allow to capture directly...

We present an extension of the recently introduced declarative process model Dynamic Condition Response Graphs (DCR Graphs) to allow nested sub-graphs and a new milestone relation between events. The extension was devel-oped during a case study carried out jointly with our industrial partner Exformat-ics, a danish provider of case and workflow mana...

We present a case study of a design of a distributed case management system using Dynamic Condition Re-sponse (DCR) Graphs, a recently proposed declarative notation for distributed processes. The case study was carried out jointly with our industrial partner Exformatics, a danish provider of knowledge and workflow man-agement systems. We present an...

Dynamic changes and evolution of workow process descrip- tions and active instances has been an active research area since the mid 1990s. Most work has been focusing on centralized workow servers executing workows described in ow-graph languages formalised as vari- ations of Petri Nets. We present a research project on Computer Sup- ported Mobile A...