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6 1 Introduction

unless more than 1 million Euro is claimed”), and the time perspective (“After two
weeks the problem is escalated”). Although there are important differences between
the various process modeling languages, we do not elaborate one these in this book.
Instead, we refer to the systematic comparisons in the context of the Workflow Pat-
terns Initiative [101, 130]. This allows us to focus on the role that process models
play in BPM.

What Are Process Models Used for?
• Insight: while making a model, the modeler is triggered to view the process
from various angles.
• Discussion: the stakeholders use models to structure discussions.
• Documentation: processes are documented for instructing people or certi-
fication purposes (cf. ISO 9000 quality management).
• Verification: process models are analyzed to find errors in systems or pro-
cedures (e.g., potential deadlocks).
• Performance analysis: techniques like simulation can be used to understand
the factors influencing response times, service levels, etc.
• Animation: models enable end users to “play out” different scenarios and
thus provide feedback to the designer.
• Specification: models can be used to describe a PAIS before it is imple-
mented and can hence serve as a “contract” between the developer and the
end user/management.
• Configuration: models can be used to configure a system.

Clearly, process models play an important role in larger organizations. When re-
designing processes and introducing new information systems, process models are
used for a variety of reasons. Typically, two types of models are used: (a) informal
models and (b) formal models (also referred to as “executable” models). Informal
models are used for discussion and documentation whereas formal models are used
for analysis or enactment (i.e., the actual execution of process). On the one end of the
spectrum there are “PowerPoint diagrams” showing high-level processes whereas on
the other end of the spectrum there are process models captured in executable code.
Whereas informal models are typically ambiguous and vague, formal models tend
to have a rather narrow focus or are too detailed to be understandable by the stake-
holders. The lack of alignment between both types of models has been discussed
extensively in BPM literature [37, 53, 90, 93, 100, 127, 131]. Here, we would like
to provide another view on the matter. Independent of the kind of model—informal
or formal—one can reflect on the alignment between model and reality. A process
model used to configure a workflow management system is probably well-aligned
with reality as the model is used to force people to work in a particular way. Unfor-
tunately, most hand-made models are disconnected from reality and provide only an
idealized view on the processes at hand. Moreover, also formal models that allow
for rigorous analysis techniques may have little to do with the actual process.