Blivet

This blivet portrays two irreconcilable perspectives at once: descending from the top are two bars with rectangular cross-section, while ascending from the bottom are three cylindrical rods.

With backgrounds to enhance the illusion

File:RogerHaywardUndecidable Monument.jpg

Hayward's "undecidable monument"

A blivet, also known as a poiuyt, devil's fork or widget, is an undecipherable figure, an optical illusion and an impossible object. It appears to have three cylindrical prongs at one end which then mysteriously transform into two rectangular prongs at the other end.

Paradoxical graphic figure

In its most common usage, the word "blivet" refers to an indecipherable figure, illustrated above. It appeared on the March 1965 cover of Mad magazine bearing the caption "Introducing 'The Mad Poiuyt' " (the last six letters on the top row of many Latin-script typewriter keyboards, right to left), and has appeared numerous times since then. An anonymously-contributed version described as a "hole location gauge" was printed in the June 1964 issue of Analog Science Fiction and Fact, with the comment that "this outrageous piece of draftsmanship evidently escaped from the Finagle & Diddle Engineering Works" (although something else called a "hole location gauge" had already been patented in 1961).

The graphic artist M. C. Escher used these types of figures as the basis for impossible three-dimensional compositions in many of his woodcut prints.

In December 1968 American optical designer and artist Roger Hayward wrote "Blivets: Research and Development" for The Worm Runner's Digest in which he presented interpretations of the blivet.

Alternative names

• Ambiguous Trident
• Devil's Pitchfork
• Devil's Tuning Fork
• Mark III Blivet
• Three-Legged Blivet
• Three-Pronged Poiuyt
• Trichotometric Indicator Support
• Three-Forked, One Slot widget (Games magazine)

External links

• Article "Impossible Fork" at MathWorld