Alternative Axiomatizations
Further information: List of logic systemsThe axiom 3 above is credited to Ćukasiewicz. The original system by Frege had axioms P2 and P3 but four other axioms instead of axiom P4 (see Frege's propositional calculus). Russell and Whitehead also suggested a system with five propositional axioms.
Read more about this topic: Hilbert System
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“If the alternative is to keep all just men in prison, or give up war and slavery, the State will not hesitate which to choose.”
—Henry David Thoreau (18171862)