When using the Lambda Calculator, you will be asked to enter predicate logic expressions. You can use the guide below to enter special symbols not found on your keyboard.
- Primes can be used in constants, and are entered with the apostrophe, e.g.
a'. - To use subscript notation to indicate the type of a constant or variable, such as xe, use an underscore, e.g.
x_eP_<e,t> - Variable types are specified using an apostrophe, followed by any alphabetic character, lowercase or uppercase, e.g.
x_'ay_'Z
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To enter some of the logical connectives, you hit a particular key or multiple keys on your keyboard but a different symbol appears on screen: ¬ ≠ ∧ → ↔ ⊕ ⊑
Connective You Type ¬ ~ ≠ != ∧ & or ^ → -> ↔ <-> ⊕ + ⊑ <: -
Other connectives require that you hold down either the ALT key on Windows and Linux computers or the CONTROL key on Macintosh computers while pressing another key:
Connective You Type ∨ ALT/CONTROL + V
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Quantifiers and other binders require that you hold down either the ALT key on Windows and Linux computers or the CONTROL key on Macintosh computers while pressing another key:
Quantifier You Type ∃ ALT/CONTROL + E ∀ ALT/CONTROL + A λ ALT/CONTROL + L ι ALT/CONTROL + I
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The set operators require that you hold down SHIFT and either the ALT key on Windows and Linux computers or the CONTROL key on Macintosh computers while pressing another key:
Operator You Type ∩ ALT/CONTROL + SHIFT + ^ ∪ ALT/CONTROL + SHIFT + V ⊆ ALT/CONTROL + < (i.e. SHIFT+,) ⊇ ALT/CONTROL + > (i.e. SHIFT+.) -
Some more complicated set operators require typing multiple keys:
Operator You Type ⊈ !, then ALT/CONTROL + < ⊊ type ALT/CONTROL + < twice ⊉ !, then ALT/CONTROL + > ⊋ type ALT/CONTROL + > twice -
The empty set symbol ∅ can be entered by pressing ALT/CONTROL plus 0 (zero).
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Numeric connectives are available as well. You just type the usual keys:
Connective You Type ⋅ (multiplication) * < < ≤ <= > > ≥ >=