Term-Algebra.js
Terms and substitions for equational reasoning.
To load it in:
const Term = require('term-algebra');From there you can create terms:
// First argument name, second argument arity
f = new Term.Func("f", 1);
g = new Term.Func("g", 2);
x = new Term.Variable("x");
y = new Term.Variable("y");
a = new Term.Constant("a");
b = new Term.Constant("b");
c = new Term.Constant("c");You can create substitutions which are mappings between variables and terms.
sigma1 = new Term.Substitution();
sigma1.add(x, g(y, c));
sigma2 = new Term.Substitution();
sigma2.add(y, a);You can compose both substitutions
sigma3 = sigma1.compose(sigma2);
console.log(sigma3.toString());
// Returns '{x -> g(a,c), y -> a}'You can apply a substitution to a term
console.log(
sigma3.apply(f(x)).toString()
);
// Returns 'f(g(a, c))'