Class World

Defined in File World.h

Class Documentation

class World

A class to represent an assignment of boolean values to propositions. A World can be partially restrictive, i.e., some propositions do not have to be assigned a value, in which case it can take on any value. Our notion of a World is similar to a set of truth assignments in propositional logic.

Public Functions

World(unsigned int numProps): Initializes a world with a given number of propositions.

bool operator[](unsigned int i) const: Returns the boolean value of a given proposition in this World. Reports an error if the proposition has not set in this World.

bool &operator[](unsigned int i): Returns the boolean value of a given proposition in this World. Creates a boolean value for the proposition if one does not already exist.

unsigned int numProps() const: Returns the number of propositions declared for this World. Not all of the propositions have necessarily been set.

bool satisfies(const World &w) const: Returns whether this World propositionally satisfies a given World w. Specifically, returns true iff for every proposition p assigned in w, p is assigned in this World and this[p] == w[p].

std::string formula() const: Returns a formatted string representation of this World, as a conjunction of literals.

const std::unordered_map<unsigned int, bool> &props() const: Returns this World’s underlying proposition-to-boolean assignment map.

bool operator==(const World &w) const: Returns whether this World is equivalent to a given World, by comparing their truth assignment maps.

void clear(): Clears this world’s truth assignment.

Protected Attributes

unsigned int numProps_

std::unordered_map<unsigned int, bool> props_

Friends

friend struct std::hash< World >