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This rule can be used forwards to derive anything from a false formula or backwards to produce a bottom formula
from which the goal line is derived.
To use it forwards:
- select both an empty line and Bottom Elimination.
- then select the bottom line you wish to use for the rule (the formula must be in the scope of the empty line).
- when prompted, enter the formula you wish to derive. This formula must not contain any predicate symbols,
function symbols or constants that are not in the signature of the box you are working in.
- the formula you entered (if valid) will appear as a new line in your proof.
To use it backwards:
- select both a goal line and Bottom Elimination.
- a new bottom goal line will be added to your proof.
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