Methodology (David Chalmers, Robert French, and D.H.) The Copycat Project: A Model of Mental Fluidity and Analogy-making (D.H. and Melanie Mitchell) Perspectives on Copycat: Comparisons with Recent Work (Melanie Mitchell and D.H.) Prolegomena to Any Future Metacat (D.H.) Tabletop, BattleOp, Ob-Platte, Potelbat, Belpatto, Platobet (D.H. and Robert French) The Emergent Personality of Tabletop, a Perception-based Model of Analogy-making (D.H. and Robert French) Letter Spirit: Esthetic Perception and Creative Play in the Rich Microcosm of the Roman Alphabet (D.H. and Gary McGraw) Summary of chapters Chapter 1: To Seek Whence Cometh a Sequence The first AI project by Hofstadter stemmed from his teenage fascination with number sequences. When he was 17, he studied the way that triangular and square numbers interleave, and eventually found a recursive relation describing it. In his first course on AI, he set to the students and to himself the task of writing a program that could extrapolate the rule by which a numeric sequence is generated. He discusses breadth-first and depth-first techniques, but eventually concludes that the results represent expert systems that incarnate a lot of technical knowledge but don't shine much light on the mental processes that humans use to solve such puzzles. Instead he devised a simplified version of the problem, called SeekWhence, where sequences are based on very simple basic rules not requiring advanced mathematical knowledge. He argues that pattern recognition, analogy, and fluid working hypotheses are fundamental to understand how humans tackle such problems. Chapter 2: The Architecture of Jumbo Jumbo is a program to solve jumbles, word puzzles consisting in five or six scrambled letters that need to be anagrammed to form an English word. The resulting word does not need to be a real one but just to a plausible, that is, to consists of a sequence of letters that is normal in English. The constituent elements of Jumbo are the following: The "chunkabet": a database of chunks, small sequences of letters, with a numeric value giving their strength as possible components of a word. The "cytoplasm": a loose data structure containing partial associations of letter, modeling a form of working memory. The name is inspired by the place in a cell where molecular fragments are assembled into proteins. The "Coderack": a structure containing "codelets", small pieces of programs that are waiting to be executed in the cytoplasm; the codelet that is executed next is chosen non-deterministically, based on urgencies