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Enter an NJ proof meeting these requirements. (You might want to work this out on scratch paper first!)
¬¬i → e∧EL∧I∨E→E
| Connective | Write (click to copy symbol to your clipboard): |
|---|---|
| Negation | |
| Conjunction | |
| Disjunction | |
| Implication | |
| Falsum |
I for introductions or E for eliminations. For disjunction introductions and conjunction eliminations, you should add in addition an L or R as appropriate. For example, you might write ∧I or ∧EL.→I, ¬I, and ∨E), add a numeral to the end of the rule name as a discharge marker. For example, you might use →I5 or ∨E23.[ and ], and put the appropriate discharge numeral immediately after that. For example, you might write [p -> q]3 to discharge the assumption p -> q with the label 3.Enter to create a new sibling node.Ctrl-Enter to create a new parent node.Ctrl-Shift-Enter to create a new child node.Tab and Shift-Tab.Ctrl-Z and Ctrl-Shift-Z.Ctrl-Backspace.Shift-Ctrl-X, Shift-Ctrl-C, and Shift-Ctrl-V