====== FAQ ======

===== How can I debug Prolog programs? =====
There is a [[http://www.swi-prolog.org/pldoc/doc_for?object=section%282,%273.5%27,swi%28%27/doc/Manual/guitracer.html%27%29%29|graphical debugger in SWI Prolog]] that is very useful to go through your program step by step, inspect the variable bindings and the open choice points.


===== Which programming language should I use for what purpose? =====
KnowRob is implemented in a combination of OWL, Prolog and Java. When creating extensions, it is worth considering which language to implement them in:

== OWL: ==
  * Description language, no programming language
  * Class taxonomy of objects, actions, events,...
  * Instances of these classes (e.g. environment models, experiences)
  * Robot capabilities/action requirements

== Prolog: ==
  * Logical programming language: conceptually close to the knowledge representation, good at searching and pattern matching
  * Useful for functionality interacting closely with the internal representation (OWL gets parsed into Prolog triples)
  * Wrapper predicates to simplify commonly used queries, inference predicates (DL inference, computables,...)
  * Functionality involving (recursive) search, graph matching, reasoning about ontological structure, ...

== C++: ==
  * Object-oriented programming language that can interact with Prolog via the [[https://www.swi-prolog.org/pldoc/doc_for?object=section(%27packages/pl2cpp.html%27)|SWIPL C++]]
  * Conceptually further away from the internal knowledge representation
  * Good library support, therefore useful for external interfaces (WWW, ROS,...)