Andreas Hess // Projects // dam²


dam² Ontology Mapping Tool

dam2 is a Java implementation of an iterative ontology mapping algorithm. The novelty of the dam2-algorithm is that it can make use of training data in the form of given mappings to a third ontology. Note that, similar to many other mapping algorithms, damSquare is limited to one-to-one mappings. dam2 can parse OWL ontologies using Jena. The mapping is output in OAEI format. Note that dam2 is not an interactive tool.

Related Publications


dam² is licensed under the terms of the GPL.

Required External Downloads

dam2 relies on Jena for parsing the ontologies and on SecondString to compute string edit distances. Please ensure that the Jena and SecondString libraries are in your classpath.


Usage of dam2 is simple. Once the required Jena and SecondString libraries are installed and added to the classpath, simply run the damSquare jar file.

dam2 Screenshot

To get started, simply select two ontologies in OWL format and a place where the mapping is to be stored, then click on "Perform Mapping". Easy, isn't it? The output is stored in the format of the Ontology Alignment Evaluation Initiative.

Note that one of the ontologies is called the reference ontology. If you want to use training data, you have to provide both a background ontology and a mapping from the background to the reference ontology, again in OAEI format, as the background mapping.

On a second tab, the dam2 user interface offers some more options to fine-tune the alignment process. The values are pre-set to sensible defaults. The meaning of the different parameters is discussed in the paper in detail.


The dam2-logo and the background image of this page are based on a painting of Amsterdam's Dam Square by Dutch painter Gerrit Berckheyde (* 1638, Haarlem - † 1698, Amsterdam).

26 Mar 2007, Andreas Hess, andreas at idirlion dot de