Every vertex has an even degree, yet the picture cannot be drawn with a single stroke.
More from Chalkdust
Let’s build a prime detector!
Bror Hjemgaard gets out his numerical toolbox
Prize crossnumber, Issue 12
£100 of MathsGear goodies to be won if you can solve it
Hiding in plain sight
Axel Kerbec gets locked out while exchanging keysPrize crossnumber, Issue 08
Win £100 of Maths Gear goodies by solving our famously fiendish crossnumber
Too good to be Truchet
Colin Beveridge looks at different designs for 2- and 3-dimensional tiles
Interstellar travel: the mathematics of wormholes
Matthew Wright looks at wormholes in sci-fi