Laws of Form

Laws of Form (hereinafter LoF) is a book by G. Spencer-Brown, published in 1969, that straddles the boundary between mathematics and philosophy. LoF describes three distinct logical systems:

Boundary algebra is Dr Philip Meguire's (2011) term for the union of the primary algebra (hereinafter abbreviated pa) and the primary arithmetic. "Laws of Form" sometimes loosely refers to the pa as well as to LoF.