It is often debated that what makes humans the ultimate intelligent species is the innate quality of doing commonsense reasoning. Humans use common sense knowledge about the world around to take appropriate decisions, and this turns out to be the necessary ingredient for their survival.
AI researches have long thought about building commonsense knowledge in AI. They argue that if AI possess necessary commonsense knowledge then it will be a truly intelligent machine.
We will discuss two major commonsense projects that exploit this idea:
- Cyc tries to build a comprehensive ontology and knowledge base of everyday commonsense knowledge. This knowledge can be used by AI applications to do human-like reasoning. Started in 1984, Cyc has come a long way. Today, OpenCyc 4.0 includes the entire Cyc ontology, containing 239,000 concepts and 2,093,000 facts and can be browsed on the OpenCyc website - http://www.cyc.com/platform/opencyc/. OpenCyc is available for download from SourceForge under an OpenCyc License.
- Never Ending Language Language Learning (NELL) is a semantic machine learning system designed by Carnegie Mellon University that is running 24/7 since the beginning of 2010. NELL is continuously browsing through millions of web pages looking for connections between different concepts. NELL tries to mimic the human learning process. NELL achieves this by performing two tasks each day
- Reading task: extract information from web text to further populate a growing knowledge base of structured facts and knowledge.
- Learning task: learn to read better each day than the day before, as evidenced by its ability to go back to yesterday’s text sources and extract more information more accurately.
NELL is successfully trying to learn new facts which you can browse at http://rtw.ml.cmu.edu/rtw/
Commonsense Reasoning systems will be an essential element in question answering systems. You can make your own question answering system using either Cyc or NELL.
Cyc, after 31 years, for the first time has been used for commercial purpose by a company called Lucid, to develop their personal assistant. Using the vast repository of Cyc’s commonsense knowledge can make your personal assistant more accurate in answering questions, compared to the assistants devoid of commonsense knowledge.
 Panton, Kathy, et al. "Common sense reasoning–from Cyc to intelligent assistant." Ambient Intelligence in Everyday Life. Springer Berlin Heidelberg, 2006. 1-31.
 Carlson, A.; Betteridge, J.; Kisiel, B.; Settles, B.; Hruschka Jr, E. R.; and Mitchell, T. M. 2010a. Toward an architecture for never-ending language learning. In AAAI, volume 5, 3.