A partially observable system is one in which the entire state of the system is not fully visible to an external

sensor A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a devi ...

. In a partially observable system the observer may utilise a memory system in order to add information to the observer's understanding of the system.

Peter Norvig Peter Norvig (born 14 December 1956) is an American computer scientist and Distinguished Education Fellow at the Stanford Institute for Human-Centered AI. He previously served as a director of research and search quality at Google. Norvig is th ...

Sebastian Thrun Sebastian Thrun (born May 14, 1967) is a German-American entrepreneur, educator, and computer scientist. He is chief executive officer of Kitty Hawk Corporation, and chairman and co-founder of Udacity. Before that, he was a Google vice preside ...

Udacity Udacity, Inc. is an American global for-profit massive open online course provider. It was founded by Sebastian Thrun, David Stavens, and Mike Sokolsky offering massive open online courses. According to Thrun, the origin of the name Udacity com ...

Introduction to Artificial Intelligence
/ref> An example of a partially observable system would be a

card game A card game is any game that uses playing cards as the primary device with which the game is played, whether the cards are of a traditional design or specifically created for the game (proprietary). Countless card games exist, including famil ...

in which some of the cards are discarded into a pile face down. In this case the observer is only able to view their own cards and potentially those of the dealer. They are not able to view the face-down (used) cards, nor the cards that will be dealt at some stage in the future. A memory system can be used to remember the previously dealt cards that are now on the used pile. This adds to the total sum of knowledge that the observer can use to make decisions. In contrast, a fully observable system would be that of

chess Chess is a board game for two players. It is an abstract strategy game that involves Perfect information, no hidden information and no elements of game of chance, chance. It is played on a square chessboard, board consisting of 64 squares arran ...

. In chess (apart from the 'who is moving next' state, and minor subtleties such as whether a side has castled, which may not be clear) the full state of the system is observable at any point in time. Partially observable is a term used in a variety of mathematical settings, including that of artificial intelligence and

partially observable Markov decision process A partially observable Markov decision process (POMDP) is a generalization of a Markov decision process (MDP). A POMDP models an agent decision process in which it is assumed that the system dynamics are determined by an MDP, but the agent cannot ...

es.

References

{{reflist Systems science