A Typescript implementation of the ELIZA chatbot. Keyword rules (keywords.ts) are a modified version of the elizaKeywords from https://github.com/brandongmwong/elizabot-js.
ELIZA was an early natural language processing computer program created by Joseph Weizenbaum in the 1960s. The program allows users to have a simple conversation with a computer. A user enters a statement and the program analyzes that statement and gives a response.
The program analyzes user statements by searching for keywords. When a keyword is found, the user's statement is transformed according to a rule associated with that keyword. If no keyword is found, the program returns a general remark or an earlier transformation. Weizenbaum uses the word "script" to describe a set of keywords and their associated transformation rules.
Each keyword is given a rank. If a user statement contains multiple keywords, then a the highest ranked keyword is used for the transformation. Furthermore, the program uses a comma or period as a delimiter. As the program scans a user statement from left to right, if it encounters a delimiter and has already found a keyword, it deletes all text after the delimiter. If no keyword has been found, then all text before the delimiter is deleted. By doing this, only single phrases or sentences are transformed.
Transformations are a combination of keywords, decomposition rules, and reassembly rules. A decomposition rule is used to break down a user's input and see if it matches certain criteria. If the input matches the criteria, an associated reassembly rule is used to create the response. Only decomposition rules containing keywords present in the user input need to be tried.
User input: It seems you hate me Keywords: YOU, ME Decomposition rule: (0 YOU 0 ME), where 0 = an indefinite # of words Reassembly rule: (What makes you think I 3 you), where 3 is a 0 index word position in the user input (hate) Response: What makes you think I hate you
User input: It seems you love and hate me Keywords: YOU, ME Decomposition rule: (0 YOU 1 ME), where 1 = one word Reassembly rule: (What makes you think I 3 you), where 3 is a 0 index word position in the user input (hate) Response: The program would return a generic response or a previous tranformation Explanation: Since there is more than a single word between YOU and ME in the user input, the decomposition rule did not have its criteria met
K = Keyword, Di = i'th Decomposition rule, Rij = j'th Reassembly rule associated with the i'th D
(K (D1, R11, ... R1m) (D2, R11, ... R2m) . . . . (Dn, Rn1, ... Rnm))
A HashMap stores {K: (Di, Ri1, ..., Rij)} key-value pairs. The keyword is used as the key and the list is used as the value.