Checks and changes expressions containing set negations using a tilde.
hastilde(x)
notilde(x)
tilde1st(x)
isNegated(x)A vector of values
Boolean expressions can be negated in various ways. For binary crisp and fuzzy sets, one of the most straightforward ways to invert the set membership scores is to subtract them from 1. This is both possible using R vectors and also often used to signal a negation in DNF (Disjunctive Normal Form) expressions.
Some other times, DNF expressions can signal a set negation (also known as the absence of a causal condition) by using lower case letters, while upper case letters are used to signal the presence of a causal condition. DNF expressions also use a tilde to signal a set negation, immediately preceding the set name.
This set of functions detect when and if a set present in a DNF expression contains a tilde
(function hastilde), whether the entire expression begins with a tilde (function
tilde1st), and also if a condition is negated (function isNegated).
# NOT RUN {
hastilde("~A")
# }
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