Not parky in a polar parka
QUESTION What are the differences between a parka and an anorak?
In technIcal terms, there is no difference. the dictionary defines both as a fleece or fur-lined waterproof jacket with a hood, worn as a protection against the cold.
Parkas are sometimes a longer length with a fur-lined hood.
the anorak was originally used for polar expeditions and is derived from the eskimo word anoraq.
the caribou Inuit described their fur coats as parkas. the style was adopted by the U.S. military as a coat worn by aircrew and soldiers stationed in cold climates. Both words started to appear in english in the 1930s.
Polar explorers wore fur-lined jackets much earlier than this. captain Robert Falcon Scott’s expedition to the antarctic between 1910 and 1912 used clothes designed by Burberry and made from wool with a waterproof outer layer.
the jackets didn’t have a hood; a scarf was worn instead. Scott’s rival polar explorer Roald amundsen wore Inuit fur clothes with a hood.
anorak has come to be used as a derogatory term to describe keen hobbyists and is synonymous with geek. this emanates from avid train enthusiasts being seen on railway station platforms in rainproof garments, with the hoods up and the drawstrings pulled tightly, so only their faces are visible.
however, this use of anorak is incorrect. a trainspotter usually wears a cagoule, a lightweight, rainproof garment that can be folded into a small bundle and stored in a rucksack.
Bob Dillon, Edinburgh.
QUESTION Why is the Collatz conjecture called ‘the simplest maths problem no one can solve’?
thIS conjecture is named after the German mathematician lothar collatz, who introduced the idea in 1937. It is an intriguing concept because it can be simply stated and yet is mathematically difficult to solve.
the collatz conjecture is the 3x + 1 problem. take any natural number and follow two simple rules: If your number is odd, multiply it by three then add one. If it is even, divide by two. Keep following these rules over and over and you will always reach the number one.
For example, if you start with 10, the sequence will be: 10 5 16 8 4 2 1.
this has been shown to work for every known number, ending in a terminal loop of 4 2 1.
the conjecture is considered unsolved in the sense that no mathematician has been able to explain why the end result is always the number one.
In more precise terminology: ‘Given a function which, like the collatz iteration, is defined by simple linear functions on various congruency classes, it is impossible to determine whether or not every number ends up at one after sufficiently many iterations.’
another well-known example is the Goldbach conjecture: every even number greater than two can be expressed as the sum of two primes.
this has been shown to hold for all integers less than 4×1018. Sian Harrison, York.
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