Taken from Making Counterfactual Assumptions by Frank Veltman.

Following MCA, alphabets are defined as lists of single-character strings.

You can use the worldgen function from genworlds.py to automatically generate the truth table corresponding to your chosen alphabet.

Formulas use a simple syntax; logical symbols are ~, |, &, >, (, ) corresponding to negation, disjunction, conjunction, implication and parentheses, respectively. Everything must be enclosed by parentheses per the usual rules, except the main connective. Thus (~(p))|(q) is correct, but ((p)>(q)) is not.

Formula updates on states are done using the updateFormula function from updates.py and law updates are done using updateLaw.

Counterfactual assumptions are done using ifItHadBeenTheCase from counterfactual.py.