10760 | With possible worlds, S4 and S5 are sound and complete, but S1-S3 are not even sound |

10751 | Second-order logic needs the sets, and its consequence has epistemological problems |

10757 | Henkin semantics has a second domain of predicates and relations (in upper case) |

10759 | There are at least seven possible systems of semantics for second-order logic |

10753 | Logical consequence is intuitively semantic, and captured by model theory |

10752 | Γ|-S says S can be deduced from Γ; Γ|=S says a good model for Γ makes S true |

10754 | In proof-theory, logical form is shown by the logical constants |

10756 | A model is a domain, and an interpretation assigning objects, predicates, relations etc. |

10758 | If models of a mathematical theory are all isomorphic, it is 'categorical', with essentially one model |

10761 | Completeness can always be achieved by cunning model-design |

10755 | A deductive system is only incomplete with respect to a formal semantics |