COGS 2160 Lecture Notes - Lecture 7: Physical Symbol System, Logic Theorist, Allen Newell

• School: York University
• Department: Cognitive Science
• Course: COGS 2160
• Professor: Jacob Beck

Document Summary

Lecture 7: classical architectures i physical symbol systems. Physical symbol systems: symbols are physical patterns, symbols on the turing machine were strokes. Functional decomposition terminates in primitive processors: p is a primitive processor if the explanation of how p works is to be provided by a more basic discipline. If the question how the multiplier subtracts one is primitive, it"s a question for the electrical engineer, not the computer scientist. If the question how you parse a sentence is primitive, it"s a question for the neurobiologist, not the cognitive scientist. The digital computer: two background ideas: binary notation, each place has two possible digits: 1 or 0. Cogs 2160: first place is the 1s (20); second is the 2s (21); third is 4s (22), etc, e. g. A simplified digital computer: adder that computes 0+0, 0+1, 1+0, and 1+1. If there"s a 0 anywhere in there, the and gate will return a 0: the x-or gate will return a value.