- published: 31 Mar 2016
- views: 49891
In computer science, A* (pronounced as "A star" ( listen)) is a computer algorithm that is widely used in pathfinding and graph traversal, the process of plotting an efficiently traversable path between multiple points, called nodes. Noted for its performance and accuracy, it enjoys widespread use. However, in practical travel-routing systems, it is generally outperformed by algorithms which can pre-process the graph to attain better performance, although other work has found A* to be superior to other approaches.
Peter Hart, Nils Nilsson and Bertram Raphael of Stanford Research Institute (now SRI International) first described the algorithm in 1968. It is an extension of Edsger Dijkstra's 1959 algorithm. A* achieves better performance by using heuristics to guide its search.
In 1968, AI researcher Nils Nilsson was trying to improve the path planning done by Shakey the Robot, a prototype robot that could navigate through a room containing obstacles. This path-finding algorithm, that Nilsson called A1, was a faster version of the then best known method, Dijkstra's algorithm, for finding shortest paths in graphs. Bertram Raphael suggested some significant improvements upon this algorithm, calling the revised version A2. Then Peter E. Hart introduced an argument that established A2, with only minor changes, to be the best possible algorithm for finding shortest paths. Hart, Nilsson and Raphael then jointly developed a proof that the revised A2 algorithm was optimal for finding shortest paths under certain well-defined conditions.
William Leonard Roberts II (born January 28, 1976), better known by his stage name Rick Ross, is an American rapper and entrepreneur.
In 2009, Ross founded the record label Maybach Music Group, on which he released his studio albums Deeper Than Rap (2009), Teflon Don (2010), God Forgives, I Don't (2012), Mastermind, Hood Billionaire (2014) and Black Market (2015). Ross was also the first artist signed to Diddy's management company Ciroc Entertainment. In early 2012, MTV named Ross as the Hottest MC in the Game.
William Leonard Roberts II was born in Clarksdale, Mississippi, and raised in Carol City, Florida. After graduating from Miami Carol City Senior High School, he attended the historically black college Albany State University on a football scholarship. Roberts worked as a correctional officer for 18 months from December 1995, until his resignation in June 1997.
In his early years at Suave House Records, Roberts initially made his debut under the pseudonym Teflon Da Don. He made his recording debut on the song "Ain't Shhh to Discuss" on Erick Sermon's lone album for DreamWorks, Def Squad Presents Erick Onasis. In the mid-2000s, he changed his name to Rick Ross. He derived his stage name from the former drug kingpin "Freeway" Rick Ross, to whom he has no connection.
There was a girl who couldn't speak
Who couldn't speak her mind
Only thing she was good at
Was telling stories of faraway lands
There was a guy who couldn't say
Who couldn't say what he wanted
Only thing he was good at
Was cracking jokes to make people laugh
So many words he swallowed
So many thoughts she kept to herself
And when they met they made love
And talked about the world and the weather
So many cities he walked
So many countries she traveled
And in their dreams they would listen