Planning algorithms are impacting technical disciplines and industries around the world, including robotics, computer-aided design, manufacturing, computer graphics, aerospace applications, drug design, and protein folding. This coherent and comprehensive book unifies material from several sources, including robotics, control theory, artificial intelligence, and algorithms. The treatment is centered on robot motion planning but integrates material on planning in discrete spaces. A major part of the book is devoted to planning under uncertainty, including decision theory, Markov decision processes, and information spaces, which are the “configuration spaces” of all sensor-based planning problems. The last part of the book delves into planning under differential constraints that arise when automating the motions of virtually any mechanical system. Developed from courses taught by the author, the book is intended for students, engineers, and researchers in robotics, artificial intelligence, and control theory as well as computer graphics, algorithms, and computational biology.

Planning Algorithms: Introductory Material

Modular Elliptic Curves and Fermat′s Last Theorem(抜粋) (フェルマ-予想がついに解けた!?)

An $(n,s)$ Davenport--Schinzel sequence, for positive integers $n$ and $s$, is a sequence composed of $n$ symbols with the properties that no two adjacent elements are equal, and that it does not contain, as a (possibly non-contiguous) subsequence, any alternation $a \cdots b \cdots a \cdots b \cdots$ of length $s+2$ between two distinct symbols $a$ and $b$. The close relationship between Davenport--Schinzel sequences and the combinatorial structure of lower envelopes of collections of functions make the sequences very attractive, because a wide variety of geometric problems can be formulated in terms of lower envelopes. A close to linear bound on the maximum length of Davenport--Schinzel sequences enable us to derive sharp bounds on the combinatorial structure underlying various geometric problems, which in turn yields efficient algorithms for these problems. This paper gives a comprehensive survey on the theory of Davenport--Schinzel sequences and their geometric applications.

http://www.math.tau.ac.il/~michas/dssurvey.pdf

Davenport-Schinzel sequences and their geometric applications

As a measure for the resemblance of curves in arbitrary dimensions we consider the so-called Frechet-distance, which is compatible with parametrizations of the curves. For polygonal chains P and Q consisting of p and q edges an algorithm of runtime O(pq log(pq)) measuring the Frechet-distance between P and Q is developed. Then some important variants are considered, namely the Frechet-distance for closed curves, the nonmonotone Frechet-distance and a distance function derived from the Frechet-distance measuring whether P resembles some part of the curve Q.

Computing the fréchet distance between two polygonal curves

We present upper and lower bounds for extremal problems defined for arrangements of lines, circles, spheres, and alike. For example, we prove that the maximum number of edges boundingm cells in an arrangement ofn lines is ?(m2/3n2/3 +n), and that it isO(m2/3n2/3s(n) +n) forn unit-circles, wheres(n) (and laters(m, n)) is a function that depends on the inverse of Ackermann's function and grows extremely slowly. If we replace unit-circles by circles of arbitrary radii the upper bound goes up toO(m3/5n4/5s(n) +n). The same bounds (without thes(n)-terms) hold for the maximum sum of degrees ofm vertices. In the case of vertex degrees in arrangements of lines and of unit-circles our bounds match previous results, but our proofs are considerably simpler than the previous ones. The maximum sum of degrees ofm vertices in an arrangement ofn spheres in three dimensions isO(m4/7n9/7s(m, n) +n2), in general, andO(m3/4n3/4s(m, n) +n) if no three spheres intersect in a common circle. The latter bound implies that the maximum number of unit-distances amongm points in three dimensions isO(m3/2s(m)) which improves the best previous upper bound on this problem. Applications of our results to other distance problems are also given.

/pdf/combinatorial-complexity-bounds-for-arrangements-of-curves-ohadh4urdn.pdf

Combinatorial complexity bounds for arrangements of curves and spheres

Let ?1,..., ?m bem simple Jordan curves in the plane, and letK1,...,Km be their respective interior regions. It is shown that if each pair of curves ?i, ?j,i ?j, intersect one another in at most two points, then the boundary ofK=?i=1mKi contains at most max(2,6m ? 12) intersection points of the curves?1, and this bound cannot be improved. As a corollary, we obtain a similar upper bound for the number of points of local nonconvexity in the union ofm Minkowski sums of planar convex sets. Following a basic approach suggested by Lozano Perez and Wesley, this can be applied to planning a collision-free translational motion of a convex polygonB amidst several (convex) polygonal obstaclesA1,...,Am. Assuming that the number of corners ofB is fixed, the algorithm presented here runs in timeO (n log2n), wheren is the total number of corners of theAi's.

/pdf/on-the-union-of-jordan-regions-and-collision-free-3nesxvrp3d.pdf

On the union of Jordan regions and collision-free translational motion amidst polygonal obstacles

On the conductors of mod/Galois representations coming from modular forms

We present several results related to the problem of estimating the complexity M(f1, ..., fn) of the pointwise minimum of n continuous univariate or bivariate functions f1, ..., fn under the assumption that no pair (resp. triple) of these functions intersect in more than some fixed number s of points. Our main result is that in the one-dimensional case M(f1, ..., fn) - O(nα(n)O(α(n)s-3)) (α(n) is the functional inverse of Ackermann's function). In the twodimensional case the problem is substantially harder, and we have only some initial estimates on M, including a tight bound Θ(n2) if s = 2, and a worst-case lower bound Ω(n2α(n)) for s ≥ 6. The treatment of the twodimensional problem is based on certain properties of the intersection patterns of a collection of planar Jordan curves, which we also develop and prove here.

On minima of function, intersection patterns of curves, and davenport-schinzel sequences

An explicit construction of locally testable codes of constant rate, constant distance and constant number of queries is given. Hence answering aﬃrmatively the c 3 -problem.

Ron Livne

Papers

On the union of Jordan regions and collision-free translational motion amidst polygonal obstacles

On the conductors of mod/Galois representations coming from modular forms

On minima of function, intersection patterns of curves, and davenport-schinzel sequences

Good Locally Testable Codes