The world is fast changing, a statement known to many people. For these people
globalization intensifies the need to adapt on events happening (e.g in stock market).
Therefore they must accomplish to retrieve and comprehend a huge amount of information
in less time. The increasing degree to which world events are captured
enhances our ability to observe global news at any time. Further, it enables us to
recollect reasons about real-world occurrences, and relate to other events. However,
due to the lack of structure and the heterogeneity of information sources, access
to this huge collection of information has been limited to browsing, searching and
reading through articles. To cope with that enormous amount of data available, Information
Extraction Systems have been developed whose goal is to extract structured
information from unstructured machine-readable documents.