A partially observable system is one in which the entire state of the system is not fully visible to an external sensor. 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. [1]
An example of a partially observable system would be a card game 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. 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 processes.
Games of patience, or (card) solitaires as they are usually called in North America, have their own 'language' of specialised terms such as "building down", "packing", "foundations", "talon" and "tableau". Once learnt they are helpful in describing, succinctly and accurately, how the games are played. Patience games are usually for a single player, although a small number have been designed for two and, in rare cases, three or even four players. They are games of skill or chance or a combination of the two. There are three classes of patience grouped by object.
Klondike, also known as Canfield, is a card game for one player and the best known and most popular version of the patience or solitaire family, something which "defies explanation" as it has one of the lowest rates of success of any such game. Partly because of that, it has spawned numerous variants including Batsford, Easthaven, King Albert, Thumb and Pouch, Somerset or Usk and Whitehead, as well as the American variants of the games, Agnes and Westcliff. The distinguishing feature of all variants is a triangular layout of the tableau, building in ascending sequence and packing in descending order.
Spit, also known as Slam or Speed, is a card game of the shedding family for two players. The game is played until all of a player's cards are gone.
Shithead is a card game, the object of which is to lose all of one's playing cards, with the final player being the "shithead". The game became popular among backpackers in the late 20th century. Although the basic structure of the game generally remains constant, there are regional variations to the game's original rules.
500 rum, also called pinochle rummy, Michigan rummy, Persian rummy, rummy 500 or 500 rummy, is a popular variant of rummy. The game of canasta and several other games are believed to have developed from this popular form of rummy. The distinctive feature of 500 rum is that each player scores the value of the sets or cards they meld. It may be played by 2 to 8 players, but it is best for 3 to 5.
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Slapjack, also known as Slaps, is a card game of the matching family, generally played among children. It can often be a child's first introduction to playing cards. The game is a cross between Beggar-My-Neighbour and Egyptian Ratscrew and is also sometimes known as Heart Attack. It is also related to the simpler 'slap' card games often called Snap.
Spite and Malice, also known as Cat and Mouse or Screw Your Neighbor, is a traditional card game for two or more players. It is a reworking of the late 19th century Continental game Crapette and is a form of competitive solitaire, with a number of variations that can be played with two or three regular decks of cards. It is descended from Russian Bank.
Artificial Intelligence: A Modern Approach (AIMA) is a university textbook on artificial intelligence, written by Stuart J. Russell and Peter Norvig. It was first published in 1995 and the fourth edition of the book was released on 28 April 2020. It is used in over 1400 universities worldwide and has been called "the most popular artificial intelligence textbook in the world". It is considered the standard text in the field of artificial intelligence.
Pyramid is a patience or solitaire game of the Simple Addition family, where the object is to get all the cards from the pyramid to the foundation.
Rummy is a group of matching-card games notable for similar gameplay based on matching cards of the same rank or sequence and same suit. The basic goal in any form of rummy is to build melds which can be either sets or runs and either be first to go out or to amass more points than the opposition.
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Speed is a game for two players or more of the shedding family of card games, in which players try to get rid of all of their cards first.
In artificial intelligence, an intelligent agent (IA) is anything which perceives its environment, takes actions autonomously in order to achieve goals, and may improve its performance with learning or may use knowledge. They may be simple or complex — a thermostat is considered an example of an intelligent agent, as is a human being, as is any system that meets the definition, such as a firm, a state, or a biome.
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 directly observe the underlying state. Instead, it must maintain a sensor model and the underlying MDP. Unlike the policy function in MDP which maps the underlying states to the actions, POMDP's policy is a mapping from the history of observations to the actions.
Tonk, or tunk, is a matching card game, which combines features of knock rummy and conquian. Tonk is a relatively fast-paced game that can be played by 2-4 players. It can be played for just points or for money wagered.
Screw is a card game where the players try to be the first to lose all their cards. Like Palace, it is derived from the Finnish card game Paskahousu.
Kalooki or Kaluki, is a version of Contract rummy popular in Jamaica, and it has become known as Jamaican Rummy. A version called "Super Kalooki" is played in tournaments, while a version called "Baby Kalooki" is often played with children or for purposes of teaching the game. There are a few variations of the game described in books and on the internet. A similar game is sometimes referred to as "Kalooki 40".
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Egyptian Ratscrew (ERS) or Slap is a modern American card game of the matching family and popular with children. The game is similar to the 19th-century British card game beggar-my-neighbour, with the added concept of "slapping" cards when certain combinations are played, similar to and perhaps borrowed from Slapjack.