  Developing ontologies can be expensive, time-consuming, as well as difficult
to develop and maintain. This is especially true for more expressive and/or
larger ontologies. Some ontologies are, however, relatively repetitive, reusing
design patterns; building these with both generic and bespoke patterns should
reduce duplication and increase regularity which in turn should impact on the
cost of development.
  Here we report on the usage of patterns applied to two biomedical ontologies:
firstly a novel ontology for karyotypes which has been built ground-up using a
pattern based approach; and, secondly, our initial refactoring of the SIO
ontology to make explicit use of patterns at development time. To enable this,
we use the Tawny-OWL library which enables full-programmatic development of
ontologies. We show how this approach can generate large numbers of classes
from much simpler data structures which is highly beneficial within biomedical
ontology engineering.
