13912 | Aristotle replace Plato's noun-verb form with unions of pairs of terms by one of four 'copulae' |

13913 | The four 'perfect syllogisms' are called Barbara, Celarent, Darii and Ferio |

13914 | Syllogistic logic has one rule: what is affirmed/denied of wholes is affirmed/denied of their parts |

13915 | Syllogistic can't handle sentences with singular terms, or relational terms, or compound sentences |

13916 | Term logic uses expression letters and brackets, and '-' for negative terms, and '+' for compound terms |

13850 | In modern logic all formal validity can be characterised syntactically |

13849 | Classical logic rests on truth and models, where constructivist logic rests on defence and refutation |

13851 | Unlike most other signs, = cannot be eliminated |

13852 | Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't |