See Also: chair form(medicine)
half-chair form(medicine)
chair(2)(dictionary)
chair(dictionary)
chair(1)(dictionary)
chair(encyclopedia)
Chair(money)
lawn chair(dictionary)
electric chair(dictionary)
Chair of the board(money)

four-colour map problem (sh) and chair form (medicine)


four-colour map problem (sh)




In topology, a long-standing conjecture asserting that no more than four colours are required to shade in any map such that each adjacent region is coloured differently.

First posed in 1852 by Francis Guthrie, a British math student, it was solved by Kenneth Appel and Wolfgang Haken using a computer-assisted proof in 1976.


chair form (medicine)


chair form


The more stable of two conformations assumed by 6-membered cyclic sugars (e.g., the pyranoses) or cyclohexane Derivatives, as opposed to boat form.

See: Haworth conformational formulas of cyclic sugars.