View source for Logical Difference Vizualiser (LogDiffViz)

{{Plugin
|Description=Logical Difference Visualizer (LogDiffViz) is a plugin for Protege-OWL
|PluginType=Tab Widget
|PluginType2=View
|ForApplication1=Protege-OWL
|Screenshot=Pinpointing.png
|DeveloperID1=William Gatens
|LastUpdated=September 12, 2011
|Topic1=Visualization
|Topic2=Versioning
|Affiliation1=University of Liverpool
}}

|free text=}}
<div style="display:block; float:left; width:100%;">

= Overview =

The LogDiffViz Plugin allows users to perform a logical difference computation between two ontologies, and allows users to view the results within the Protege-OWL editor.
A logical difference computation aims to calculate the difference between two ontologies taking into account the semantic meaning of the underlying description logics on which ontology languages are built, rather than syntactical or structural differences. The theoretical background for this approach is described in a paper [http://dx.doi.org/10.1007/978-3-540-71070-7_21 The Logical Difference Problem for Description Logic Terminologies] by Boris Konev, Dirk Walther and Frank Wolter

Internally the LogDiffViz plugin uses a tool called CEX2 which does the core computation in the logical difference visualisation process (the plugin is simply a front-end to the CEX tool). More information about the CEX tool can be found at [http://www.csc.liv.ac.uk/~michel/software/cex2/]


'''NOTE:'''
The LogDiffViz plugin is a experimental prototype plugin and is by no means stable or guaranteed to work for every ontology. For details please see the below

= How to use it = 

== Visualizing a logical difference computation ==

The basic steps of visualising a logical difference computation between to ontologies:

# Enable the LogDiffViz tab: Window > Tabs > Logical Difference Visualizer
# Open the Control Panel from the menu: Tools > Difference... Visualization
##Select and load an ontology into the first box
##Select and load an ontology into the second box
##Choose a signature option (see below)
##Press "Visualize"

You should now get a display of the logical difference visualization. 
The two ontologies you selected will be loaded into the top half of the tab and the logical difference will be loaded into the bottom half.
Each ontology (and differences) takes on a tree like structure so you can navigate the axioms of the ontology by expanding and collapsing the tree.



=== Signature Options ===
A signature is the union of concept and role names for a given ontology and can be used generate a logical difference computation based on a particular set of concept and role names, rather than simply generating an arbitrary set of differences. 

Using the control panel you can choose which signature will be used either:

* The signature of the first ontology
* The signtaure of the second ontology
* A "shared" signature - The intersection of the signature of the first and second ontologies
* A custom signature - which can be any subset of the complete signature - generated by the signature tool found in the "Tools" menu

== Toolbar Options ==

=== Axiom Pinpointing (Explanations) ===

To see '''why''' a particular generated difference (to perform axiom pinpointed based on a particular difference axiom) has been calculated between two ontologies:

# Ensure you have a reasoner configured and started (tested with HermiT and FaCT++).
# Select a leaf node of the "Differences" ontology tree
# Press the green arrow on the toolbar

The minimal pinpointing set (explaination of axioms) will now be highlighted on the original source ontologies in the top half of the logical difference tab.

=== Signature Overview ===
To see what signature was originally selected after calculating the logical difference press the sigma (&Sigma;) button on the toolbar.

= Limitations and known issues =

* Only currently works on the Linux operating system
* Limited to ontologies supported currently by CEX ("acyclic ELHr terminologies, i.e. EL terminologies with additional domain restrictions, range restrictions, and (simple) role inclusions")
* Axiom pinpointing only currently works with ontologies in the KRSS format (OWL ontologies need to be converted)

= Screenshots =


'''Click for larger image'''

[[File:controlpanel.png | left | text-top | thumb | Control Panel ]]

[[File:Mainpanel.png | left | text-top | thumb | Main Panel ]]

[[File:Pinpointing.png | left | text-top | thumb | Axiom pinpointing ]]