Tangle (mathematics)

In mathematics, the word tangle usually refers to one of two related concepts:

In link theory, a tangle is an embedding of n arcs and m circles into – the difference from the previous definition is that it includes circles as well as arcs, and partitions the boundary into two (isomorphic) pieces, which is algebraically more convenient – it allows one to add tangles by stacking them, for instance.

(A quite different use of 'tangle' appears in Graph minors X. Obstructions to tree-decomposition by N. Robertson and P. D. Seymour, J. Combinatorial Theory B 59 (1991) 153--190, who used it to describe separation in graphs. This usage has been extended to matroids.)

The balance of this article discusses Conway's sense of tangles; for the link theory sense, see that article.

Two n-tangles are considered equivalent if there is an ambient isotopy of one tangle to the other keeping the boundary of the 3-ball fixed. Tangle theory can be considered analogous to knot theory except instead of closed loops we use strings whose ends are nailed down. See also braid theory.

Tangle (series 3)

The third series of Tangle, an Australian drama television series, was confirmed in December 2010, and production began in June 2011 and ended in August. Series three will contain six episodes, and is written by Fiona Seres and Tony McNamara, and directed by Emma Freeman and Michael James Rowland.

Cast

Episodes

References

Surge

Surge may refer to:

Science

Popular culture

Surge (glacier)

Glacial surges are short-lived events where a glacier can advance substantially, moving at velocities up to 100 times faster than normal. Surging glaciers cluster around a few areas. High concentrations of surging glaciers occur in Svalbard, the Canadian Arctic islands, Alaska and Iceland. In some glaciers, surges can occur in fairly regular cycles, with 15 to 100 or more surge events per year. In other glaciers, surging remains unpredictable. In some glaciers, however, the period of stagnation and build-up between two surges typically lasts 10 to 200 years and is called the quiescent phase. During this period the velocities of the glacier are significantly lower, and the glaciers can retreat substantially.

Types of glacier surges

Glacier surges have been divided into two categories depending on the character of the surge event. Glaciers in Alaska exhibit surges with a sudden onset, extremely high (tens of meters/day)maximum flow rate and a sudden termination, often with a discharge of stored water. These are called Alaskan-type surges and it is suspected that these surges are hydrologically controlled.

Transformers (toy line)

The Transformers (トランスフォーマー, Toransufomā) is a line of toys produced by the Japanese company Takara (now known as Takara Tomy) and American toy company Hasbro. The Transformers toyline was created from toy molds mostly produced by Japanese company Takara in the toylines Diaclone and Microman. Other toy molds from other companies such as Bandai were used as well. In 1984, Hasbro bought the distribution rights to the molds and rebranded them as the Transformers for distribution in North America. Hasbro would go on to buy the entire toy line from Takara, giving them sole ownership of the Transformers toy-line, branding rights, and copyrights, while in exchange, Takara was given the rights to produce the toys and the rights to distribute them in the Japanese market. The premise behind the Transformers toyline is that an individual toy's parts can be shifted about to change it from a vehicle, a device, or an animal, to a robot action figure and back again. The taglines "More Than Meets The Eye" and "Robots In Disguise" reflect this ability.