logic-oracle

a.k.a The Oracle of Knights & Knaves

A module for deducing answers to yes-no questions on the Island of Knights & Knaves

Installation

npm i answer-deducer

Usage

First import the package:

import deducer from 'answer-deducer'
//OR
const deducer = require('answer-deducer')

Then ask a question:

const answer = deducer(identities, answerer, question)

Input	Syntax
identities	object containing names and roles for all characters in your game, ex. {A: 'K', B: 'N'}
answerer	string naming the character the question is directed to, ex. 'A'
question (no connectives)	[array] of two elements: 1. a question/predicate string, ex. 'Same' and 2. an [array] of names or quantifiers.*
question (with connectives)	object containing two or more question arrays as outlined above and the relevant connective, e.g. AND. See example below.

For example, the question 'Is either A or B a Knight but not both?' is represented by the following object:

const question = {
  1: {
    1: ['Knight', ['A']],
    2: ['Knight' ['B']],
    c: 'OR'
  },
  2: {
    1: {
      1: ['Knight', ['A']],
      2: ['Knight' ['B']],
      c: 'AND'
    },
    c: 'NOT'
  },
  c: 'AND'
}

*See Questions for the full list of predicates, connectives, and quantifiers.

The deducer function returns true or false in the voice of the character specified as answerer. So, if the specified character is a Knave and the statement is true the module will return false. See below for more on character identities.

Identities

You may name your characters any string you wish, though tradition would have it that your first character's name starts with 'A' and your second with 'B', etc. Character names are keys in your identities object with roles as values. Possible values for roles are the following:

Value	Name	Speaks
'K'	Knight	the truth, always
'N'	Knave	only lies
'D'	Dragon	the truth, except in the presence of a Knight
'M'	Monk	whatever they wish*

*Currently, this implemented by returning a random choice of true or false when a Monk is asked a question, but we hope to add craftier monks soon!