Lippard.Multics 1986-02-19 15:54:23 mst Wed Subject: The Naive Dog Physics Manifesto Date: Wed, 19 Feb 86 13:03:03 PST From: Pavel.pa@Xerox.COM To: Info-COBOL@MC.LCS.MIT.EDU Message-ID: <860219-130321-3127@Xerox> Forwarding history at end. --Pavel ---------------------------------------------------------------- SEMINAR From PDP to NDP through LFG: The Naive Dog Physics Manifesto Garrison W. Cottrell Department of Dog Science Condominium Community College of Southern California The Naive Physics Manifesto (Hayes, 1978) was a seminal paper in extending the theory of knowledge representation to everyday phenomena. The goal of the present work is to extend this approach to Dog Physics, using the connectionist (or PDP) framework to encode our everyday, commonsense knowledge about dogs in a neural network[1]. However, following Hayes, the goal is not a working computer program. That is in the province of so-called performance theories of Dog Physics (see, for example, my 1984 Modelling the Intentional Behavior of the Dog). Such efforts are bound to fail, since they must correspond to empirical data, which is always changing. Rather, we will first try to design a competence theory of dog physics[2], and, as with Hayes and Chomsky, the strategy is to continually refine that, without ever getting to the performance theory. The approach taken here is to develop a syntactic theory of dog actions which is constrained by Dog Physics. Using a variant of Bresnan's Lexical-Functional Grammar, our representation will be an context-free action grammar, with associated s-structures (situation structures). The s-structures are defined in terms of Situation Dogmatics[3], and are a partial specification of the situation of the dog during that action. Here is a sample grammar which generates strings of action predicates corresponding to dog days[4], (nonterminals are capitalized): Day -> Action Day | Sleep Action -> Sleep | Eat | Play | leavecondo Walk Sleep -> dream Sleep | deaddog Sleep | wake Eat -> Eat chomp | chomp Play -> stuff(Toy, mouth) | hump(x,y) | getpetted(x,y) Toy -> ball | sock Walk -> poop Walk | trot Walk | sniff Walk | entercondo Several regularities are captured by the syntax. For example, these rules have the desirable property that pooping in the condo is ungrammatical. Obviously such grammatical details are not innate in the infant dog. This brings us to the question of rule acquisition and Universality. These context-free action rules are assumed to be learned by a neural network with "hidden" units[5] using the bark propagation method (see Rumelhart & McClelland, 1985; Cottrell 1985). The beauty of this is that Dogmatic Universality is achieved by assuming neural networks to be innate[6]. The above rules generate some impossible sequences, however. This is the job of the situation equation annotations. Some situations are impossible, and this acts as a filter on the generated strings. For example, an infinite string of stuff(Toy, mouth)'s are prohibited by the constraint that the situated dog can only fit one ball and one sock in her mouth at the same time. One of the goals of Naive Dog Physics is to determine these commonsense constraints. One of our major results is the discovery that dog force (df) is constant. Since df = mass * acceleration, this means that smaller dogs accelerate faster, and dogs at rest have infinite mass. This is intuitively appealing, and has been borne out by my dogs. ____________________ [1]We have decided not to use FOPC, as this has been proven by Schank (personal communication) to be inadequate, in a proof too loud to fit in this footnote. [2]The use of competence theories is a standard trick first intro- duced by Chomsky, which avoids the intrusion of reality on the theory. An example is Chomsky's theory of light bulb changing, which begins by rotating the ceiling... [3]Barwoof & Peppy (1983). Situation Dogmatics (SD) can be regarded as a competence theory of reality. See previous footnote. Using SD is a departure from Hayes, who exhorts us to "understand what [the represen- tation] means." In the Gibsonian world of Situation Dogmatics, we don't know what the representation means. That would entail information in our heads. Rather, following B&P, the information is out there, in the dog. Thus, for example, the dog's bark means there are surfers walking behind the condo. [4]Of course, a less ambitious approach would just try to account for dog day afternoons. [5]It is never clear in these models where these units are hidden, or who hid them there. The important thing is that you can't see them. [6]Actually this assumption may be too strong when applied to the dogs under consideration. However, this is much weaker than Pinker's as- sumption that the entirety of Joan Bresnan's mind is innate in the language learner. It is instructive to see how his rules would work here. We assume hump(x,y) is innate, and x is bound by the default s- function "Self". The first time the puppy is humped, the mismatch causes a new Passive humping entry to be formed, with the associated redundancy rule. Evidence for the generalization to other predicates is seen in the puppy subsequently trying to stuff her mouth into the ball. 9 ==================== Jack, take special note of dog physics. could we extend this to a theory of naive dog lmechanics? Uri, note use of LFG to solve semantics problems Valeriy, here's agood use of connectionism. :-) ======================================================================== Thought you might find this amusing... --eve ---------------------------------------------------------------- Date: 18 Feb 86 21:18 PST (Tuesday) From: haynes@decwrl.DEC.COM (Charles Haynes) To: Lighthearted^.pa Cc: Whimsy^.pa, joel@decwrl.DEC.COM, karlin@su-sushi.ARPA, larrabee@decwrl.DEC.COM, woods.pa Subject: The Naive Dog Physics Manifesto Date: Tue, 18 Feb 86 21:03:22 pst From: mcgregor (Scott McGregor) To: haynes, jed@sail, mcdaniel, wilkins@sri-ai Subject: Dogs; FYA Date: Tue, 18 Feb 86 17:45:13 pst From: drewry (Raymond Drewry) To: mcgregor Subject: dogs the footnote about schank is most revealing... --r Date: Tue, 18 Feb 86 16:34:46 PST From: Eve Schooler To: drewry@decwrl, david@uchistem.BITNET Date: Sun, 16 Feb 86 11:18:45 PST From: Dr. Michael G. Dyer To: airheads Date: Thu, 13 Feb 86 21:09:15 PST From: cottrell@nprdc.arpa (Gary Cottrell) To: ics@nprdc.arpa Subject: Naive Dog Physics Manifesto