List of isthmuses

An isthmus (/ˈɪsθməs/ or /ˈɪsməs/; plural: isthmuses; from Ancient Greek: ἰσθμός isthmos "neck") is a narrow piece of land connecting two larger areas across an expanse of water that otherwise separates them. A tombolo is an isthmus that consists of a spit or bar.

Canals are often built across isthmuses, where they may be a particularly advantageous short cut for marine transport. The Panama Canal crosses the Isthmus of Panama, connecting the North Atlantic and Pacific Oceans; the Suez Canal connects the Mediterranean Sea and the Indian Ocean, cutting across the western side of an isthmus formed by the Sinai Peninsula. An example in the United Kingdom is the Crinan Canal, which crosses the isthmus between Loch Crinan and Loch Gilp, which connects the Kintyre peninsula with the rest of Scotland.

A strait is the sea counterpart of isthmus.

Africa

Egypt

Tait conjectures

The Tait conjectures are three conjectures made by 19th-century mathematician Peter Guthrie Tait in his study of knots. The Tait conjectures involve concepts in knot theory such as alternating knots, chirality, and writhe. All of the Tait conjectures have been solved, the most recent being the Tait flyping conjecture proven in 1991 by Morwen Thistlethwaite and William Menasco.

Background

Tait came up with his conjectures after his attempt to tabulate all knots in the late 19th century. As a founder of the field of knot theory, his work lacks a mathematically rigorous framework, and it is unclear whether the conjectures apply to all knots, or just to alternating knots. Most of them are only true for alternating knots. In the Tait conjectures, a knot diagram is reduced if all the isthmi (nugatory crossings) have been removed.

Crossing number of alternating knots

Tait conjectured that in certain circumstances, crossing number was a knot invariant, specifically:

In other words, the crossing number of a reduced, alternating link is an invariant of the knot. This conjecture was proven by Morwen Thistlethwaite, Louis Kauffman and K. Murasugi in 1987, using the Jones polynomial.

Isthmus (newspaper)

Isthmus is an alternative weekly newspaper based in Madison, Wisconsin (US). It was founded in 1976. The paper, which is printed on Thursdays, has a weekly circulation of 50,000. It also runs Isthmus.com, a local website.

Isthmus takes its name from the land mass that forms the heart of Madison’s downtown and houses the twin engines of the city’s economy, the University of Wisconsin—Madison and the Wisconsin State Capitol. The paper was founded by Vincent P. O'Hern and Fred Milverstedt, the latter a Madison area journalist and the former a Madison transplant originally from Detroit. It was O'Hern and Milverstedt who came up with the paper's somewhat ominous original motto, "To the Death," a mantra that, according to O'Hern, "expressed our determination to succeed," though he noted that "no life has been lost in [the paper's] production." Milverstedt served as original editor of Isthmus until leaving the paper in 1980. O'Hern would remain as the paper's publisher, and write a weekly "Making the Paper" column; his wife, Linda Baldwin, also served as associate publisher.