  In the systems and software modeling field, a conceptual model involves
modeling with concepts to support development and design. An example of a
conceptual model is a description developed using the Unified Modeling Language
(UML). UML uses a model multiplicity formulation approach, wherein a number of
models are used to represent alternative views. By contrast, a model
singularity approach uses only a single integrated model. Each of these styles
of modeling has its strengths and weaknesses. This paper introduces a partial
solution to the issue of multiplicity vs. singularity in modeling by adopting
UML use cases and class models into the conceptual thinging machine (TM) model.
To apply use cases, we adopt the observation that a use-case diagram is a
description that shows the internal structure of the part of the system
represented by the use case in addition to being useful to people outside of
the system. Additionally, the UML class diagram is recast in TM representation.
Accordingly, we develop a TMUML model that embraces the TM specification of the
UML class diagram and the internal structure extracted from the UML use case.
TMUML modeling introduces some of the advantages that have made UML a popular
modeling language to TM modeling. At the same time, this approach supplies UML
with partial model singularity. The paper details experimentation with TMUML
using examples from the literature. Our results indicate that mixing UML with
other models could be a viable approach.
