notebook/notes/formal-system/proof-system/natural-deduction.md

13 KiB

title TARGET DECK FILE TAGS tags
Natural Deduction Obsidian::STEM formal-system::natural-deduction
logic
natural-deduction
programming

Overview

Natural deduction is a proof system typically used alongside classical truth-functional prop-logic and pred-logic logic. It is meant to mimic the patterns of reasoning that one might "naturally" make when forming arguments in plain English.

%%ANKI Basic Why is natural deduction named the way it is? Back: It is mean to mimic the patterns of reasoning one might "naturally" make when forming arguments in plain English. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

Axioms

Natural deduction is interesting in that it has no axioms.

%%ANKI Basic How many axioms does natural deduction include? Back: 0 Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

Inference Rules

Scoped to just propositional logic, there are 10 inference rules corresponding to an "introduction" and "elimination" of each propositional logic operator. When extending to predicate logic, we also include an introduction and elimination rule for both the pred-logic#Existentials and pred-logic#Universals quantifers.

%%ANKI Basic With respect to propositional logic, how many inference rules does natural deduction include? Back: 10 Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic With respect to predicate logic, how many inference rules does natural deduction include? Back: 14 Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How are natural deduction's inference rules categorized into two? Back: As introduction and elimination rules. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic With respect to propositional logic, how are natural deduction's inference rules categorized into five? Back: As an introduction and elimination rule per propositional logic operators. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

Negation

For proposition E1, \neg{\text{-}}I{:} \quad \text{TODO} and \neg{\text{-}}E{:} \quad \text{TODO}

Conjunction

For propositions E_1, \ldots, E_n, \land{\text{-}}I{:} \quad \begin{array}{c} E_1, \ldots, E_n \ \hline E_1 \land \cdots \land E_n \end{array} and \land{\text{-}}E{:} \quad \begin{array}{c} E_1 \land \cdots \land E_n \ \hline E_i \end{array}

%%ANKI Basic In natural deduction, how is conjunction introduction denoted? Back: As \land{\text{-}}I. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic In natural deduction, how is conjunction elimination denoted? Back: As \land{\text{-}}E. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How is \land{\text{-}}I expressed in schematic notation? Back: \begin{array}{c} E_1, \ldots, E_n \ \hline E_1 \land \cdots \land E_n \end{array} Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How is \land{\text{-}}E expressed in schematic notation? Back: \begin{array}{c} E_1 \land \cdots \land E_n \ \hline E_i \end{array} Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Which natural deduction inference rule is used in the following? \begin{array}{c} P, Q, R \ \hline P \land R \end{array} Back: \land{\text{-}}I Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Which natural deduction inference rule is used in the following? \begin{array}{c} P \land Q \ \hline P \end{array} Back: \land{\text{-}}E Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

Disjunction

For propositions E_1, \ldots, E_n, \lor{\text{-}}I{:} \quad \begin{array}{c} E_i \ \hline E_1 \lor \cdots \lor E_n \end{array} and \lor{\text{-}}E{:} \quad \begin{array}{c} E_1 \lor \cdots \lor E_n, E_1 \Rightarrow E, \ldots, E_n \Rightarrow E \ \hline E \end{array}

%%ANKI Basic In natural deduction, how is disjunction introduction denoted? Back: As \lor{\text{-}}I. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic In natural deduction, how is disjunction elimination denoted?? Back: As \lor{\text{-}}E. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How is \lor{\text{-}}I expressed in schematic notation? Back: \lor{\text{-}}I{:} \quad \begin{array}{c} E_i \ \hline E_1 \lor \cdots \lor E_n \end{array} Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How is \lor{\text{-}}E expressed in schematic notation? Back: \lor{\text{-}}E{:} \quad \begin{array}{c} E_1 \lor \cdots \lor E_n, E_1 \Rightarrow E, \ldots, E_n \Rightarrow E \ \hline E \end{array} Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Which natural deduction inference rule is used in the following? \begin{array}{c} P, Q \ \hline R \lor P \end{array} Back: \lor{\text{-}}I Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Which natural deduction inference rule is used in the following? \begin{array}{c} P \lor Q, P \Rightarrow R, Q \Rightarrow R \ \hline P \end{array} Back: \lor{\text{-}}E Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

Implication

For propositions E_1, \ldots, E_n, {\Rightarrow}{\text{-}}I: \quad \begin{array}{c} \text{from } E_1, \cdots, E_n \text{ infer } E \ \hline (E_1 \land \cdots \land E_n) \Rightarrow E \end{array} and {\Rightarrow}{\text{-}}E: \quad \begin{array}{c} E_1 \Rightarrow E_2, E_1 \ \hline E_2 \end{array}

%%ANKI Basic In natural deduction, how is implication introduction denoted? Back: As {\Rightarrow}{\text{-}}I. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How is {\Rightarrow}{\text{-}}I expressed in schematic notation? Back: {\Rightarrow}{\text{-}}I: \quad \begin{array}{c} \text{from } E_1, \cdots, E_n \text{ infer } E \ \hline (E_1 \land \cdots \land E_n) \Rightarrow E \end{array} Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic In natural deduction, how is implication elimination denoted? Back: As {\Rightarrow}{\text{-}}E. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Modus ponens is associated with which propositional logic operator? Back: \Rightarrow Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Does modus ponens correspond to an introduction or elimination rule? Back: Elimination. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Cloze Natural deduction rule {1:\Rightarrow}-{1:E} is also known as {modus ponens}. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How is {\Rightarrow}{\text{-}}E expressed in schematic notation? Back: \begin{array}{c} E1 \Rightarrow E2, E1 \ \hline E2 \end{array} Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How is modus ponens expressed in schematic notation? Back: \begin{array}{c} E1 \Rightarrow E2, E1 \ \hline E2 \end{array} Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Which natural deduction inference rule is used in the following? \begin{array}{c} P \Rightarrow Q, P \ \hline R \end{array} Back: N/A. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Which natural deduction inference rule is used in the following? \begin{array}{c} P \Rightarrow Q, P \ \hline Q \end{array} Back: {\Rightarrow}{\text{-}}E Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

Biconditional

For propositions E1 and E2, {\Leftrightarrow}{\text{-}}I: \quad \begin{array}{c} E1 \Rightarrow E2, E2 \Rightarrow E1 \ \hline E1 \Leftrightarrow E2 \end{array} and {\Leftrightarrow}{\text{-}}E: \quad \begin{array}{c} E1 \Leftrightarrow E2 \ \hline E1 \Rightarrow E2, E2 \Rightarrow E1 \end{array}

%%ANKI Basic In natural deduction, how is biconditional introduction denoted? Back: As {\Leftrightarrow}{\text{-}}I. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic In natural deduction, how is biconditional elimination denoted? Back: As {\Leftrightarrow}{\text{-}}E. Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How is {\Leftrightarrow}{\text{-}}I expressed in schematic notation? Back: \begin{array}{c} E1 \Rightarrow E2, E2 \Rightarrow E1 \ \hline E1 \Leftrightarrow E2 \end{array} Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Which natural deduction inference rule is used in the following? \begin{array}{c} P \Rightarrow Q, Q \Rightarrow P \ \hline Q \Leftrightarrow P \end{array} Back: {\Leftrightarrow}{\text{-}}I Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic How is {\Leftrightarrow}{\text{-}}E expressed in schematic notation? Back: \begin{array}{c} E1 \Leftrightarrow E2 \ \hline E1 \Rightarrow E2, E2 \Rightarrow E1 \end{array} Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

%%ANKI Basic Which natural deduction inference rule is used in the following? \begin{array}{c} P \Leftrightarrow Q \ \hline Q \Rightarrow P \end{array} Back: {\Leftrightarrow}{\text{-}}E Reference: Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.

END%%

Existential Quantification

TODO

Universal Quantification

TODO

Bibliography

  • Gries, David. The Science of Programming. Texts and Monographs in Computer Science. New York: Springer-Verlag, 1981.