List of rules
Introduction
Symbol | Reads | Argument Semantics |
---|---|---|
^I | And Introduction | from x, y deduce x ^ y |
->I | Implication Introduction | from "assuming x deduces y", deduce x -> y |
/I | Or Introduction | from x deduce x / ? or ? / x |
~I | Not Introduction | from "assuming original deduces bottom" deduce its negation |
~~I | Double Negation Introduction | from x deduce ~~x |
FI | Falsity Introduction | from x and ~x deduce F |
TI | Truth Introduction | from nothing deduces T (but why would you do that?) |
<->I | Equivalence Introduction | from x -> y and y -> x deduce x <-> y |
existsI | Exists Introduction | from 𝝓(x) deduce ∃a 𝝓(a) |
forallI | Forall Introduction | from "c deduces f(c)" deduce ∀x f(x) |
Elimination
Symbol | Reads | Argument Semantics |
---|---|---|
^E | And Elimination | from x ^ y deduce x (or y) |
->E | Emplication Elimination | from x -> y and x deduce y |
/E | Or Elimination | from x1 / x2, "assuming x1 deduces y", "assuming x2 deduces y", deduce y |
~E | Not Elimination | from x and ~x deduces F (same as FI) |
~~E | Double Negation Elimination | from ~~x deduce x |
FE | Falsity Elimination | from F deduce anything |
<->E | Equivalence Elimination | from x <-> y and either side, deduce the other side |
existsE | Exists Elimination | from ∃a 𝝓(a) and "𝝓(c) for some c deduces x", deduce x |
forallE | Forall Elimination | from ∀x f deduce f[x/c] |
forall->E | Forall Implication Elimination | from ∀x f(x) -> g(x) and f(c), deduces g(c) |
Special
Symbol | Reads | Argument Semantics |
---|---|---|
LEM | Law of Excluded Middle | from nothing deduce p / ~p |
MT | Modus Tollens | from x -> y and ~y, deduce ~x |
PC | Proof by Contradiction | from "assuming x deduces F", deduce ~x |
refl | rule of Reflection | from nothing deduce x = x |
=sub | Equality Substitution | from a = b and f(a), deduce f(b) |
sym | rule of Symmetry | from a = b deduce b = a |
forall I const | forall I const | introduces a new free variable |
given | Given | given proposition / formula |
premise | Premise | given proposition / formula |
ass | Assumption | assume proposition / formula |
tick | Tick | from x deduce x (to improve readability) |