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  "body": "\n## Problem\n\nThe **three utilities problem**, also known as **water, gas and electricity**, is a mathematical puzzle that asks for non-crossing connections to be drawn between three houses and three utility companies on a plane. When posing it in the early 20th century, Henry Dudeney wrote that it was already an old problem. It is an impossible puzzle: it is not possible to connect all nine lines without any of them crossing. Versions of the problem on nonplanar surfaces such as a [[torus|03NM7DZXXC]] or [[Möbius strip|04AJE0M271]], or that allow connections to pass through other houses or utilities, can be solved.\n",
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