logicUSLIB/logicus-fol/3.3.0

LogicUS.FOL.DeductionSystems

Deduction systems for first-order logic ready to use with LogicUS.FOL.Deduction, as text that can be edited: rules can be removed, renamed or added before reading it with readSystem. The rules of the connectives are those of LogicUS.PL.DeductionSystems (package logicus-pl).

Presets

type alias Preset =
{ name : String
, description : String
, rules : String
}

A system with a name and a short description.

presets : List Preset

The systems of this module. They have the same names as their propositional versions in LogicUS.PL.DeductionSystems.

presetSystem : String -> Maybe System

The system of a preset, by name.

Rules

Classical natural deduction for first-order logic with equality: the rules of the connectives (intuitionistic and classical), and those of the quantifiers and of equality.

The rules of the quantifiers. In ∀I and ∃E the term a must be new (a variable or a constant that does not occur in the open assumptions nor in the conclusion).

equalityRules : String

Reflexivity and Leibniz law (substitution of equals).

derivedRules : String

Rules that can be derived from the others, for exercises that allow them: those of LogicUS.PL.DeductionSystems (MT, DS, HS, ¬¬I, LEM, De Morgan laws) and the negation of the quantifiers.

axiomatic : String

The axiomatic system of LogicUS.PL.DeductionSystems extended to first-order logic: two axiom schemes of the universal quantifier and the generalization rule.