In graph theory, a flow network (also known as a transportation network) is a directed graph where each edge has a capacity and each edge receives a flow. The amount of flow on an edge cannot exceed the capacity of the edge. Often in Operations Research, a directed graph is called a network, the vertices are called nodes and the edges are called arcs. A flow must satisfy the restriction that the amount of flow into a node equals the amount of flow out of it, except when it is a source, which has more outgoing flow, or sink, which has more incoming flow. A network can be used to model traffic in a road system, fluids in pipes, currents in an electrical circuit, or anything similar in which something travels through a network of nodes.

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Lindsey Stirling (born on September 21, 1986) is an American violinist, musician, dancer, performance artist, and composer. In 2010 she competed on the fifth season of America's Got Talent. Stirling is noted for her versatility performing music from country to hip hop.

At the age of 23 Stirling was a quarter-finalist on the fifth season of America's Got Talent where she was known as the ‘Hip Hop Violinist’. After Stirling's performance, Sharon Osbourne said, "Wow... we love you Lindsey!” and Piers Morgan called her performance "Electrifying!".

At the age of 5, after being influenced by the classic music records played by her father, Stirling requested the opportunity to learn and play the violin.

Stirling was classically trained through private lessons for 12 years. When she was 16, she joined a rock band with four friends called Stomp on Melvin. As part of her experience with Stomp on Melvin, Stirling wrote a solo violin rock song, and her performance helped her to win both the title of Arizona’s Jr. Miss in 2005 and the talent category of the National Jr. Miss Pageant. As of May 2, 2012, Stirling is 5'3" tall.

Seongha Jeong (정성하) (colloquially: Sungha Jung) (born 2 September 1996) is a South Korean professional acoustic finger-style guitarist who has risen to fame on YouTube and other sites. As of 2012, his channel had over 17 million views, with his videos getting a total of over 454 million views, and also over 726,000 subscribers.

Seongha typically takes three days to learn and practice a new piece, and video-record it for upload onto YouTube. His genre selection is rather broad, as he learns and plays many pieces that are playable on guitar, therefore consequently spread across numerous genres.

Seongha has won 13 awards on YouTube, including 6 "#1" awards. Also on YouTube, Seongha has 523 videos with over one million views. Seongha's video with the most views is the one which shows him playing the theme from "Pirates Of The Caribbean".

In 2010, he was featured on Narsha's solo album "Narsha" for the song "I'm in Love" Seongha has composed 18 pieces as of February 2011, two of which are featured in his debut album, "Perfect Blue". He released his second album, "Irony", on 21 September 2011.