four-color problem

[ fawr-kuhl-er, fohr- ]

/ ˈfɔrˈkʌl ər, ˈfoʊr- /

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noun Mathematics.

the problem, solved in 1976, of proving the theorem that any geographic map can be colored using only four colors so that no connected countries with a common boundary are colored the same color.

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Also called four-color theorem.

Origin of four-color problem

First recorded in 1875–80

Words nearby four-color problem

four-by-two, four-channel, fourché, fourchette, four-color, four-color problem, four-colour, four-corners, four-cycle, four-deal bridge, four-dimensional

How to use four-color problem in a sentence

Several times, either because they forgot or they had a technical problem, they connected directly, and we could see them.
Was Sony Hit With a Second Hack?|Shane Harris|January 8, 2015|DAILY BEAST
There are four photos there of representative presidential candidates.
Today’s GOP: Still Cool With Racist Pandering?|Michael Tomasky|January 7, 2015|DAILY BEAST
Four weeks after the injections, all 20 of the participants had developed the antibodies needed to stave off the infection.
The Race for the Ebola Vaccine|Abby Haglage|January 7, 2015|DAILY BEAST
Every once in a while, they act swiftly and acknowledge the problem.
Today’s GOP: Still Cool With Racist Pandering?|Michael Tomasky|January 7, 2015|DAILY BEAST

Even other men of color considered Revels a curious figure, for Mississippi had never had a large free black population.
The Black Man Who Replaced Jefferson Davis in the Senate|Philip Dray|January 7, 2015|DAILY BEAST
A little boy of four was moved to passionate grief at the sight of a dead dog taken from a pond.
Children's Ways|James Sully
The pink flowers are the largest while those of a yellow color are the smallest.
Tobacco; Its History, Varieties, Culture, Manufacture and Commerce|E. R. Billings.
In cross-section the burrows varied from round (three inches in diameter) to oval (three inches high and four inches wide).
Summer Birds From the Yucatan Peninsula|Erwin E. Klaas
Before the spinet a bench was placed about four feet below the keys, and I was put upon the bench.
Gulliver's Travels|Jonathan Swift
We had six field-pieces, but we only took four, harnessed wit twice the usual number of horses.
Blackwood's Edinburgh Magazine, No. CCCXXXIX. January, 1844. Vol. LV.|Various