Frederick Smith, David Walker, and Greg Morrisett. Alias types. Technical Report TR99-1773, Cornell University, October 1999.  Home/Search   Document Not in Database   Summary   Related Articles   Check

....can be subdivided into batch and online techniques. The former provide sophisticated techniques to cope with perceptual ambiguities [2, 24, 30] but they can only generate maps after extensive batch processing. Online techniques are specifically suited to acquire maps as the robot navigates [6, 27], which is of great practical importance in many navigation and exploration problems [25] Today s most widely used online algorithms are based on extended Kalman filters (EKFs) based on a seminal series of papers [17, 18, 27, 26] EKFs calculate Gaussian posteriors over the locations of ....

.... techniques are specifically suited to acquire maps as the robot navigates [6, 27] which is of great practical importance in many navigation and exploration problems [25] Today s most widely used online algorithms are based on extended Kalman filters (EKFs) based on a seminal series of papers [17, 18, 27, 26]. EKFs calculate Gaussian posteriors over the locations of environmental features and the robot itself. A key bottleneck of EKFs which has been subject to intense research is their computational complexity. The standard EKF approach requires time quadratic in the number of features in the ....

R. C. Smith and P. Cheeseman. On the representation and estimation of spatial uncertainty. Technical Report TR 4760 & 7239, SRI, 1985.

....over time, making the problem of acquiring an accurate map challenging. The SLAM problem has attracted immense attention in the past a few years [4] This paper addresses computational issues in performing realworld SLAM. The classical SLAM solution, based on the extended Kalman filter (EKF) [8, 9, 12, 11], scales quadratically with the number of landmarks in the map. As a result, practical implementations of this approach are limited to a few hundred landmarks [2] This deficiency has long been recognized and has spurred a flurry of research on more efficient SLAM algorithms. One thrust of ....

R. C. Smith and P. Cheeseman. On the representation and estimation of spatial uncertainty. Technical Report TR 4760 & 7239, SRI, 1985.

....it in a distinct way from class structure and functionalities. We propose a reification of such mechanism by means of inter object relationships. So, the proposed model is self described, in the sense that inheritance semantics is expressed in terms of class methods. Researches on procedural [Smi82] or computational reflection [BKK 86, Mae87, BDG 88, Fer89, KdRB91] have shown the interest of reflexive architectures. Our language, named flo 1 is an object oriented programming language. It extends the object oriented paradigms by integrating relationship management. It is based on ....

Brian Cantwell Smith. Reflection and semantics in a procedural lnaguage. Technical Report TR-272, MIT, Cambridge, MA, 1982.

....system. These three features are necessary to offer an efficient and extensible management of dependencies. We will show in section 3.3 how we can use the metaobjects to extend the expressiveness of the language and to propose different controls. Many researches which deal with procedural [Smi82] or computational reflection [BKK 86, BDG 88, Mae87, KdRB91] have been realized. We have chosen to base our meta object implementation on Ferber s work [Fer89] Ferber replies to the following question: how can we represent meta objects in a class based language He proposes three ....

Brian Cantwell Smith. Reflection and semantics in a procedural lnaguage. Technical Report TR272, MIT, Cambridge, MA, 1982.

....P ( Gamma P (sj ) P ( 6) P ( Gamma P ( Z P ( d Gamma1 (normalization) 7) 3. For each action command a do: P ( Gamma Z P ( j ; a) P ( d (8) Most existing probabilistic state estimation methods are variants of this basic algorithmic scheme (see e.g. [2, 5, 6, 7, 8, 9, 11, 13, 15, 14]) some of which date back to the early sixties. As apparent from this incremental rule, three probabilities must be known for probabilistic state estimation: 1. The initial probability P ( also called a prior. 2. The conditional probability P (sj ) usually referred to as the (probabilistic) ....

R. C. Smith and P. Cheeseman. On the representation and estimation of spatial uncertainty. Technical Report TR 4760 & 7239, SRI, 1985.

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Frederick Smith, David Walker, and Greg Morrisett. Alias types. Technical Report TR99-1773, Cornell University, October 1999.

....standard features for a type system. Still, these features do appear in other type systems for low level languages. For instance, TALx86 [15] the Typed Assembly Language implementation, contains a state component for reasoning about aliasing and stateful operations such as object deallocation [26]. Both Dependent ML and TALx86 contain a collection of predicates for reasoning about arithmetic so that programs can eliminate array bounds checks. The fact that there can be significant reuse of many of the type constructors in our language makes the trusted computing base more manageable. It ....

Frederick Smith, David Walker, and Greg Morrisett. Alias types. Technical Report TR99-1773, Cornell University, October 1999.

....theorem captures this idea formally: Theorem 1 (Soundness) If # S : C and ; C; # # # and (S, #) # # . # # (S # ,# # ) then (S # ,# # ) is not a stuck state. We prove soundness syntactically in the style of Wright and Felleisen [28] The proof appears in the companion technical report [19]. 4 Non linear Constraints Most linear type systems contain a class of non linear values that can be used in a completely unrestricted fashion. Our system is similar in that it admits non linear constraints, written # ## # # . They are characterized by the axiom: # # # ## # # = # ....

....the type of multiple aliases; both r 1 and its alias on the stack sp[1] can be used as integer references in the else clause. Future loads of r 1 or its alias will not have to perform a null check. These additional features of our language are also proven sound in the companion technical report [19]. Syntax: types # : ##1, # n# null values v : null instructions # : mknull x, #; # tosum v, ##1, # n# ifnull v then #1 else #2 Operational semantics: S, mknull x, #; #) # # (S # ## null ,#[# #] ptr(#) x] where # ## S (S, tosum v, ....

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Frederick Smith, David Walker, and Greg Morrisett. Alias types. Technical Report TR99-1773, Cornell University, October 1999.

....S : C and ; C; and (S; 7 : 7 (S 0 ; 0 ) then (S 0 ; 0 ) is not a stuck state. We prove soundness syntactically in the style of Wright and Felleisen [28] Due to space considerations, we cannot include the proof in this paper. It appears in a companion technical report [19]. 3 Non linear Constraints Most linear type systems contain a class of non linear values that can be used in a completely unrestricted fashion. Our system is similar in that it admits non linear constraints, written f 7 g . They are characterized by the axiom: f 7 g = f 7 g ....

....types. Our new system allows us to treat memory more uniformly. In fact, our new language can encode stack types similar to those described by Morrisett [11] except that activation records are allocated on the heap rather than using a conventional call stack. The companion technical report [19] shows how to compile a simple imperative language in such a way that it allocates and deletes its own stack frames. The development of our language was inspired by the Calculus of Capabilities [4] CC) CC provides an alternative to the region based type system developed by Tofte and Talpin ....

Frederick Smith, David Walker, and Greg Morrisett. Alias types. Technical Report TR99-1773, Cornell University, October 1999.

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R. C. Smith and P. Cheeseman. On the representation and estimation of spatial uncertainty. Technical Report TR 4760 & 7239, SRI, 1985.

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