Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185374
Tomás Feder, Eyal Kushilevitz, M. Naor
The authors study the direct sum problem with respect to communication complexity: Consider a function f: D to (0, 1), where D contained in (0, 1)/sup n/*(0, 1)/sup n/. The amortized communication complexity of f, i.e. the communication complexity of simultaneously computing f on l instances, divided by l is studied. The authors present, both in the deterministic and the randomized model, functions with communication complexity Theta (log n) and amortized communication complexity O(1). They also give a general lower bound on the amortized communication complexity of any function f in terms of its communication complexity C(f).<>
{"title":"Amortized communication complexity","authors":"Tomás Feder, Eyal Kushilevitz, M. Naor","doi":"10.1109/SFCS.1991.185374","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185374","url":null,"abstract":"The authors study the direct sum problem with respect to communication complexity: Consider a function f: D to (0, 1), where D contained in (0, 1)/sup n/*(0, 1)/sup n/. The amortized communication complexity of f, i.e. the communication complexity of simultaneously computing f on l instances, divided by l is studied. The authors present, both in the deterministic and the randomized model, functions with communication complexity Theta (log n) and amortized communication complexity O(1). They also give a general lower bound on the amortized communication complexity of any function f in terms of its communication complexity C(f).<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121143897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185418
T. Hsu, V. Ramachandran
The problem of finding the smallest set of edges whose addition triconnects an undirected graph is considered. This is a fundamental graph-theoretic problem that has applications in designing reliable networks and fault-tolerant computing. A linear time sequential algorithm is given for the problem. This is a substantial improvement over the best previous algorithm for this problem, which runs in O(n(n+m)/sup 2/) time on a graph with n vertices and m edges.<>
{"title":"A linear time algorithm for triconnectivity augmentation","authors":"T. Hsu, V. Ramachandran","doi":"10.1109/SFCS.1991.185418","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185418","url":null,"abstract":"The problem of finding the smallest set of edges whose addition triconnects an undirected graph is considered. This is a fundamental graph-theoretic problem that has applications in designing reliable networks and fault-tolerant computing. A linear time sequential algorithm is given for the problem. This is a substantial improvement over the best previous algorithm for this problem, which runs in O(n(n+m)/sup 2/) time on a graph with n vertices and m edges.<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121327168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185399
I. Emiris, J. Canny
Algorithms modeled as algebraic branching programs, with inputs from an infinite ordered field, are studied. Direct perturbations on the input, so that an algorithm designed under the assumption of nondegeneracy can be applied to all inputs, are described. A deterministic method for algorithms with determinant tests and a randomized one for arbitrary test expressions are defined. They both incur extra complexity factors that are constant in several cases. Moreover, polynomial and exponential time algorithms always remain in the same complexity class while being enhanced with the power to execute on arbitrary inputs. Both methods are distinguished by their conceptual elegance and are significantly faster than previous ones.<>
{"title":"A general approach to removing degeneracies","authors":"I. Emiris, J. Canny","doi":"10.1109/SFCS.1991.185399","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185399","url":null,"abstract":"Algorithms modeled as algebraic branching programs, with inputs from an infinite ordered field, are studied. Direct perturbations on the input, so that an algorithm designed under the assumption of nondegeneracy can be applied to all inputs, are described. A deterministic method for algorithms with determinant tests and a randomized one for arbitrary test expressions are defined. They both incur extra complexity factors that are constant in several cases. Moreover, polynomial and exponential time algorithms always remain in the same complexity class while being enhanced with the power to execute on arbitrary inputs. Both methods are distinguished by their conceptual elegance and are significantly faster than previous ones.<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123087285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185422
L. Lovász, M. Naor, I. Newman, A. Wigderson
The relative power of determinism, randomness, and nondeterminism for search problems in the Boolean decision tree model is studied. It is shown that the CNF search problem is complete for all the variants of decision trees. It is then shown that the gaps between the nondeterministic, the randomized, and the deterministic complexities can be arbitrarily large for search problems. The special case of nondeterministic complexity is discussed.<>
{"title":"Search problems in the decision tree model","authors":"L. Lovász, M. Naor, I. Newman, A. Wigderson","doi":"10.1109/SFCS.1991.185422","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185422","url":null,"abstract":"The relative power of determinism, randomness, and nondeterminism for search problems in the Boolean decision tree model is studied. It is shown that the CNF search problem is complete for all the variants of decision trees. It is then shown that the gaps between the nondeterministic, the randomized, and the deterministic complexities can be arbitrarily large for search problems. The special case of nondeterministic complexity is discussed.<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"221 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127525134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185385
M. Paterson, Uri Zwick
It is shown that a random restriction leaving only a fraction in of the input variables unassigned reduces the expected de Morgan formula size of the induced function by a factor of O( in /sup 1.63/). This is an improvement over previous results. The new exponent yields an increased lower bound of approximately n/sup 2.63/ for the de Morgan formula size of a function in P defined by A.E. Andreev (1987). This is the largest lower bound known, even for functions in NP.<>
结果表明，随机限制只留下一小部分未分配的输入变量，将诱导函数的期望de Morgan公式大小降低了0 (in /sup 1.63/)。这是对以前结果的改进。新的指数为A.E. Andreev(1987)定义的P中的函数的de Morgan公式大小提供了大约n/sup 2.63/的增加下界。这是已知的最大下界，即使对于NP中的函数也是如此
{"title":"Shrinkage of de Morgan formulae under restriction","authors":"M. Paterson, Uri Zwick","doi":"10.1109/SFCS.1991.185385","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185385","url":null,"abstract":"It is shown that a random restriction leaving only a fraction in of the input variables unassigned reduces the expected de Morgan formula size of the induced function by a factor of O( in /sup 1.63/). This is an improvement over previous results. The new exponent yields an increased lower bound of approximately n/sup 2.63/ for the de Morgan formula size of a function in P defined by A.E. Andreev (1987). This is the largest lower bound known, even for functions in NP.<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"40 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131491243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185451
A. Kanevsky, R. Tamassia, G. Battista, Jianer Chen
Given a graph G with n vertices and m edges, a k-connectivity query for vertices v' and v" of G asks whether there exist k disjoint paths between v' and v". The authors consider the problem of performing k-connectivity queries for k>
{"title":"On-line maintenance of the four-connected components of a graph","authors":"A. Kanevsky, R. Tamassia, G. Battista, Jianer Chen","doi":"10.1109/SFCS.1991.185451","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185451","url":null,"abstract":"Given a graph G with n vertices and m edges, a k-connectivity query for vertices v' and v\" of G asks whether there exist k disjoint paths between v' and v\". The authors consider the problem of performing k-connectivity queries for k<or=4. First, they present a static data structure that answers such queries in O(1) time. Next, they consider the problem of performing queries intermixed with online updates that insert vertices and edges. For triconnected graphs they give a dynamic data structure that supports queries and updates in time O( alpha (l,n)) amortized, where n is the current number of vertices of the graph and l is the total number of operations performed ( alpha (l, n) denotes the slowly growing Ackermann function inverse). For general graphs, a sequence of l operations takes total time O(n log n+l). All of the above data structures use space O(n), proportional to the number of vertices of the graph. The results also yield an efficient algorithm for testing whether graph G is four-connected that runs in O(n alpha (n, n)+m) time using O(n+m) space.<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"39 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132679987","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185341
U. Feige, S. Goldwasser, L. Lovász, S. Safra, M. Szegedy
The computational complexity of approximating omega (G), the size of the largest clique in a graph G, within a given factor is considered. It is shown that if certain approximation procedures exist, then EXPTIME=NEXPTIME and NP=P.<>
{"title":"Approximating clique is almost NP-complete","authors":"U. Feige, S. Goldwasser, L. Lovász, S. Safra, M. Szegedy","doi":"10.1109/SFCS.1991.185341","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185341","url":null,"abstract":"The computational complexity of approximating omega (G), the size of the largest clique in a graph G, within a given factor is considered. It is shown that if certain approximation procedures exist, then EXPTIME=NEXPTIME and NP=P.<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130035422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185425
R. Reischuk, Bernd Schmeltz
Boolean circuits in which gates independently make errors with probability (at most) epsilon are considered. It is shown that the critical number crit(f) of a function f yields lower bound Omega (crit(f) log crit (f)) for the noisy circuit size. The lower bound is proved for an even stronger computational model, static Boolean decision trees with erroneous answers. A decision tree is static if the questions it asks do not depend on previous answers. The depth of such a tree provides a lower bound on the number of gates that depend directly on some input and hence on the size of a noisy circuit. Furthermore, it is shown that an Omega (n log n) lower bound holds for almost all Boolean n-input functions with respect to the depth of noisy dynamic decision trees. This bound is the best possible and implies that almost all n-input Boolean functions have noisy decision tree complexity Theta (n log n) in the static as well as in the dynamic case.<>
{"title":"Reliable computation with noisy circuits and decision trees-a general n log n lower bound","authors":"R. Reischuk, Bernd Schmeltz","doi":"10.1109/SFCS.1991.185425","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185425","url":null,"abstract":"Boolean circuits in which gates independently make errors with probability (at most) epsilon are considered. It is shown that the critical number crit(f) of a function f yields lower bound Omega (crit(f) log crit (f)) for the noisy circuit size. The lower bound is proved for an even stronger computational model, static Boolean decision trees with erroneous answers. A decision tree is static if the questions it asks do not depend on previous answers. The depth of such a tree provides a lower bound on the number of gates that depend directly on some input and hence on the size of a noisy circuit. Furthermore, it is shown that an Omega (n log n) lower bound holds for almost all Boolean n-input functions with respect to the depth of noisy dynamic decision trees. This bound is the best possible and implies that almost all n-input Boolean functions have noisy decision tree complexity Theta (n log n) in the static as well as in the dynamic case.<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133434353","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185404
Y. Aumann, M. Ben-Or
A scheme for emulating the parallel random access machine (PRAM) on a faulty hypercube is presented. All components of the hypercube, including the memory modules, are assumed to be subject to failure. The faults may occur at any time during the emulation and the system readjusts dynamically. The scheme, which rests on L.G. Valiant's BSP model (1990), is the first to achieve optimal and work-preserving PRAM emulation on a dynamically faulty network.<>
{"title":"Asymptotically optimal PRAM emulation on faulty hypercubes","authors":"Y. Aumann, M. Ben-Or","doi":"10.1109/SFCS.1991.185404","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185404","url":null,"abstract":"A scheme for emulating the parallel random access machine (PRAM) on a faulty hypercube is presented. All components of the hypercube, including the memory modules, are assumed to be subject to failure. The faults may occur at any time during the emulation and the system readjusts dynamically. The scheme, which rests on L.G. Valiant's BSP model (1990), is the first to achieve optimal and work-preserving PRAM emulation on a dynamically faulty network.<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"246 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114194042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1991-09-01DOI: 10.1109/SFCS.1991.185381
A. Fiat, Dean Phillips Foster, H. Karloff, Y. Rabani, Yiftach Ravid, S. Vishwanathan
A layered graph is a connected, weighted graph whose vertices are partitioned into sets L/sub 0/=(s), L/sub 1/, L/sub 2/, . . ., and whose edges run between consecutive layers. Its width is max( mod L/sub i/ mod ). In the online layered graph traversal problem, a searcher starts at s in a layered graph of unknown width and tries to reach a target vertex t; however, the vertices in layer i and the edges between layers i-1 and i are only revealed when the searcher reaches layer i-1. The authors give upper and lower bounds on the competitive ratio of layered graph traversal algorithms. They give a deterministic online algorithm that is O(9w)-competitive on width-w graphs and prove that for no w can a deterministic online algorithm have a competitive ratio better than 2w/sup -2/ on width-w graphs. They prove that for all w, w/2 is a lower bound on the competitive ratio of any randomized online layered graph traversal algorithm. For traversing layered graphs consisting of w disjoint paths tied together at a common source, they give a randomized online algorithm with a competitive ratio of O(log w) and prove that this is optimal up to a constant factor.<>
{"title":"Competitive algorithms for layered graph traversal","authors":"A. Fiat, Dean Phillips Foster, H. Karloff, Y. Rabani, Yiftach Ravid, S. Vishwanathan","doi":"10.1109/SFCS.1991.185381","DOIUrl":"https://doi.org/10.1109/SFCS.1991.185381","url":null,"abstract":"A layered graph is a connected, weighted graph whose vertices are partitioned into sets L/sub 0/=(s), L/sub 1/, L/sub 2/, . . ., and whose edges run between consecutive layers. Its width is max( mod L/sub i/ mod ). In the online layered graph traversal problem, a searcher starts at s in a layered graph of unknown width and tries to reach a target vertex t; however, the vertices in layer i and the edges between layers i-1 and i are only revealed when the searcher reaches layer i-1. The authors give upper and lower bounds on the competitive ratio of layered graph traversal algorithms. They give a deterministic online algorithm that is O(9w)-competitive on width-w graphs and prove that for no w can a deterministic online algorithm have a competitive ratio better than 2w/sup -2/ on width-w graphs. They prove that for all w, w/2 is a lower bound on the competitive ratio of any randomized online layered graph traversal algorithm. For traversing layered graphs consisting of w disjoint paths tied together at a common source, they give a randomized online algorithm with a competitive ratio of O(log w) and prove that this is optimal up to a constant factor.<<ETX>>","PeriodicalId":320781,"journal":{"name":"[1991] Proceedings 32nd Annual Symposium of Foundations of Computer Science","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1991-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121105086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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