- Mount Rainier National Park (/reɪ.ˈnɪər/ ray-NEER) is a national park of the United States located in southeast Pierce County and northeast Lewis County in the U.S. state of Washington. The park was established on March 2, 1899, as the fourth national park in the United States, preserving 236,381 acres (369.3 sq mi; 956.6 km2) including all of Mount Rainier, a 14,410-foot (4,390 m) stratovolcano. The mountain rises abruptly from the surrounding land with elevations in the park ranging from 1,600 feet to over 14,000 feet (490–4,300 m). The highest point in the Cascade Range, Mount Rainier is surrounded by valleys, waterfalls, subalpine meadows, and 91,000 acres (142.2 sq mi; 368.3 km2) of old-growth forest. More than 25 glaciers descend the flanks of the volcano, which is often shrouded in clouds that dump enormous amounts of rain and snow.
- Well-ordering theorem (Wikipedia)
In mathematics, the well-ordering theorem, also known as Zermelo’s theorem, states that every set can be well-ordered. A set X is well-ordered by a strict total order if every non-empty subset of X has a least element under the ordering. The well-ordering theorem together with Zorn’s lemma are the most important mathematical statements that are equivalent to the axiom of choice (often called AC, see also Axiom of choice § Equivalents). Ernst Zermelo introduced the axiom of choice as an “unobjectionable logical principle” to prove the well-ordering theorem. One can conclude from the well-ordering theorem that every set is susceptible to transfinite induction, which is considered by mathematicians to be a powerful technique. One famous consequence of the theorem is the Banach–Tarski paradox.