A Direct Sum Theorem holds in a model of computation, when for every problem solving some k input instances together is k times as expensive as solving one. We show that Direct Sum Theorems hold in the models of deter...
详细信息
A Direct Sum Theorem holds in a model of computation, when for every problem solving some k input instances together is k times as expensive as solving one. We show that Direct Sum Theorems hold in the models of deterministic and randomized decisiontrees for all relations. We also note that a near optimal Direct Sum Theorem holds for quantum decisiontrees for boolean functions. (C) 2010 Elsevier B.V. All rights reserved.
We discuss several complexity measures for Boolean functions: certificate complexity, sensitivity, block sensitivity, and the degree of a representing or approximating polynomial. We survey the relations and biggest g...
详细信息
We discuss several complexity measures for Boolean functions: certificate complexity, sensitivity, block sensitivity, and the degree of a representing or approximating polynomial. We survey the relations and biggest gaps known between these measures, and show how they give bounds for the decision tree complexity of Boolean functions on deterministic, randomized, and quantum computers. (C) 2002 Elsevier Science B.V. All rights reserved.
We prove that the randomized decision tree complexity of the recursive majority- of- three is Omega(2.55(d)), where d is the depth of the recursion. The proof is by a bottom up induction, which is same in spirit as th...
详细信息
ISBN:
(数字)9783642392061
ISBN:
(纸本)9783642392061
We prove that the randomized decision tree complexity of the recursive majority- of- three is Omega(2.55(d)), where d is the depth of the recursion. The proof is by a bottom up induction, which is same in spirit as the one in the proof of Saks and Wigderson in their 1986 paper on the complexity of evaluating game trees. Previous work includes an Omega (7/3)(d)) lower bound, published in 2003 by Jayram, Kumar, and Sivakumar. Their proof used a top down induction and tools from information theory. In 2011, Magniez, Nayak, Santha, and Xiao, improved the lower bound to Omega((5/2)(d)) and the upper bound to O(2.64946(d)).
For a Boolean function f:{0, 1}(n) ->{0, 1} computed by a Boolean circuit Cover a finite basis B, the energy complexityof C(denoted by ECB(C)) is the maximum over all inputs {0, 1}(n) of the number gates of the cir...
详细信息
For a Boolean function f:{0, 1}(n) ->{0, 1} computed by a Boolean circuit Cover a finite basis B, the energy complexityof C(denoted by ECB(C)) is the maximum over all inputs {0, 1}(n) of the number gates of the circuit C(excluding the inputs) that output a one. Energy complexity of a Boolean function over a finite basis Bdenoted by ECB(f) (def)= min(C) ECB(C) where Cis a Boolean circuit over Bcomputing f. We study the case when B={boolean AND(2), boolean OR(2), (sic)}, the standard Boolean basis. It is known that any Boolean function can be computed by a circuit (with potentially large size) with an energy of at most 3n(1 + is an element of(n)) for a small is an element of(n)(which we observe is improvable to 3n - 1). We show several new results and connections between energy complexity and other wellstudied parameters of Boolean functions. For all Boolean functions f, EC(f) <= O(DT(f)(3)) where DT(f) is the optimal decisiontree depth of f. We define a parameter positive sensitivity(denoted by psens), a quantity that is smaller than sensitivity (Cook et al. 1986, [3]) and defined in a similar way, and show that for any Boolean circuit Ccomputing a Boolean function f, EC(C) >= psens(f)/3. For a monotone function f, we show that EC(f) = Omega(KW+ (f)) where KW+ (f) is the cost of monotone Karchmer-Wigderson game of f. Restricting the above notion of energy complexity to Boolean formulas, we show EC(F) = Omega(root L(F)-Depth(F)) where L(F) is the size and Depth(F) is the depth of a formula F. (C) 2020 Elsevier B.V. All rights reserved.
We establish a lower bound of Omega(rootn) on the bounded-error quantum query complexity of read-once Boolean functions. The result is proved via an inductive argument, together with an extension of a lower bound meth...
详细信息
We establish a lower bound of Omega(rootn) on the bounded-error quantum query complexity of read-once Boolean functions. The result is proved via an inductive argument, together with an extension of a lower bound method of Ambainis. Ambainis' method involves viewing a quantum computation as a mapping from inputs to quantum states (unit vectors in a complex inner-product space) which changes as the computation proceeds. Initially the mapping is constant (the state is independent of the input). If the computation evalutes the function f then at the end of the computation the two states associated with any f-distinguished pair of inputs (having different f values) are nearly orthogonal. Thus the inner product of their associated states must have changed from 1 to nearly 0. For any set off-distinguished pairs of inputs, the sum of the inner products of the corresponding pairs of states must decrease significantly during the computation, By deriving an upper bound on the decrease in such a sum, during a single step, for a carefully selected set of input pairs, one can obtain a lower bound on the number of steps. We extend Ambainis' bound by considering general weighted sums off-distinguished pairs. We then prove our result for read-once functions by induction on the number of variables, where the induction step involves a careful choice of weights depending on f to optimize the lower bound attained. (C) 2004 Elsevier Inc. All rights reserved.
For a Boolean function f, let D(f) denote its deterministic decision tree complexity, i.e., minimum number of (adaptive) queries required in worst case in order to determine f. In a classic paper, Rivest and Vuillemin...
详细信息
For a Boolean function f, let D(f) denote its deterministic decision tree complexity, i.e., minimum number of (adaptive) queries required in worst case in order to determine f. In a classic paper, Rivest and Vuillemin [11] show that any non-constant monotone property P : {0, 1}((n/2)) -> {0, 1} of n-vertex graphs has D(P) = Omega (n(2)). We extend their result to 3-uniform hypergraphs. In particular, we show that any non-constant monotone property P : {0, 1}((n/3)) -> {0, 1} of n-vertex 3-uniform hypergraphs has D (P) = Omega (n(3)). Our proof combines the combinatorial approach of Rivest and Vuillemin with the topological approach of Kahn, Saks, and Sturtevant [6]. Interestingly, our proof makes use of Vinogradov's Theorem (weak Goldbach Conjecture), inspired by its recent use by Babai et al. [1] in the context of the topological approach. Our work leaves the generalization to k-uniform hypergraphs as an intriguing open question. (C) 2014 Elsevier B.V. All rights reserved.
We propose a new model of stringent oracle access defined for a general complexity class. For example, when comparing the power of two machine models relative to some oracle set X, we restrict that machines of both ty...
详细信息
We propose a new model of stringent oracle access defined for a general complexity class. For example, when comparing the power of two machine models relative to some oracle set X, we restrict that machines of both types ask queries from the same segment of the set X. In particular, for investigating polynomial-time (or polynomial-size) computability, we propose polynomial stringency, bounding query length to any fixed polynomial of input length. Under such stringent oracle access, we show an oracle G such that BPPG = PHG. (C) 2004 Elsevier B.V. All rights reserved.
More than 30 years ago, Karp conjectured that all nontrivial monotone graph properties are evasive, i.e., have decision tree complexity ((n)(2)), where n is the number of vertices. It was proved in 1984 by Kahn, Saks,...
详细信息
More than 30 years ago, Karp conjectured that all nontrivial monotone graph properties are evasive, i.e., have decision tree complexity ((n)(2)), where n is the number of vertices. It was proved in 1984 by Kahn, Saks, and Sturtevant [Combinatorica, 4 (1984), pp. 297-306] if n is a prime power by a topological approach. Using their method, we prove a lower bound of 1/3 n(2) - o(n(2)) for general n.
We prove new results on evasiveness of monotone graph properties by extending the techniques of Kahn, Saks, and Sturtevant [Combinatorica, 4 (1984), pp. 297-306]. For the property of containing a subgraph isomorphic t...
详细信息
We prove new results on evasiveness of monotone graph properties by extending the techniques of Kahn, Saks, and Sturtevant [Combinatorica, 4 (1984), pp. 297-306]. For the property of containing a subgraph isomorphic to a fixed graph, and a fairly large class of related n-vertex graph properties, we show evasiveness for an arithmetic progression of values of n. This implies a 1/2n(2)-O (n) lower bound on the decision tree complexity of these properties. We prove that properties that are preserved under taking graph minors are evasive for all sufficiently large n. This greatly generalizes a theorem due to Best, van Emde Boas, and Lenstra [A Sharpened Version of the Aanderaa-Rosenberg Conjecture, Report ZW 30/74, Mathematisch Centrum, Amsterdam, The Netherlands, 1974] which states that planarity is evasive. We prove a similar result for bipartite subgraph containment.
Turan (1984) [11] initiated the study of the sensitivity complexity of graph properties. He conjectured that for any non-trivial graph properties on n vertices, the sensitivity complexity is at least n-1. He proved an...
详细信息
Turan (1984) [11] initiated the study of the sensitivity complexity of graph properties. He conjectured that for any non-trivial graph properties on n vertices, the sensitivity complexity is at least n-1. He proved an left perpendicularn/4right perpendicular lower bound for sensitivity in his paper: Turan (1984) [11]. Wegener (1985) [12] proved this conjecture for all monotone graph properties. In this paper we improve Turan's lower bound to 6/17n (approximate to 0.35n). We hope that this will shed some light on the proof of Turan's conjecture. (C) 2011 Elsevier B.V. All rights reserved.
暂无评论