Truth function
Named by 3 essays across one field — each of them below, with the objects they name alongside it.
A formula is a corner of a cube
A formula about three letters is a set of eight rows. Written as a table that is a list; drawn on a cube it is a shape — and the shape is what almost every later question in this field turns out to be about.
One connective is enough
Of the sixteen ways to combine two truth values, exactly two can build all the others by themselves. Which two is not obvious, and the reason turns out to be five properties that a connective either has or escapes.
The map that puts neighbours side by side
Reorder the rows of a truth table so that neighbouring squares differ in one letter, and finding a short formula stops being algebra and becomes the problem of covering a shape with rectangles.
Named alongside it
The objects these essays reach for when they reach for this one.
ConnectiveHypercubeNormal formAffine functionAssignmentClosureCoveringDualityFunctional completenessGray codeKarnaugh mapMinimality