# What is the origin of the prefix logic notation used in WFF 'N PROOF?

The classic "modern logic" game of WFF 'N PROOF uses a set of symbols to represent logical relations that I've seen used nowhere else: $C$ for then; $A$ for or; $K$ for and; $E$ for if and only if; and $N$ for not. These are used in prefix notation so that, for example $$CNpq$$ means $$\neg p\Rightarrow q,$$ and $$EpAqNr$$ means $$p\Leftrightarrow \left({q\vee\neg r}\right).$$

What is the origin of these symbols and have they been used widely or elsewhere? Are they still in use?

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Your link contains a recent forum thread debating that very question. –  Henning Makholm Oct 4 '11 at 18:52

It's polish notation. For example, $K$ stands for koniunkcja, from the same root as "conjunction".

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It was called "Polish notation" because of people who could not remember the name Łukasiewicz. –  GEdgar Oct 4 '11 at 18:47
Some examples of the use of this notation. –  raxacoricofallapatorius Oct 5 '11 at 12:48