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310
On counterexamples to the Hughes conjecture
"... described counterexamples for p = 5, 7 and 11. Finite groups which do not satisfy the conjecture, antiHughes groups, have interesting properties. We give explicit constructions of a number of antiHughes groups via powercommutator presentations, including relatively small examples with orders 5 4 ..."
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described counterexamples for p = 5, 7 and 11. Finite groups which do not satisfy the conjecture, antiHughes groups, have interesting properties. We give explicit constructions of a number of antiHughes groups via powercommutator presentations, including relatively small examples with orders 5
A counterexample to King’s conjecture
 Compos. Math
"... Abstract. King’s conjecture states that on every smooth complete toric variety X there exists a strongly exceptional collection which generates the bounded derived category of X and which consists of line bundles. We give a counterexample to this conjecture. This example is just the Hirzebruch surfa ..."
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Cited by 23 (4 self)
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Abstract. King’s conjecture states that on every smooth complete toric variety X there exists a strongly exceptional collection which generates the bounded derived category of X and which consists of line bundles. We give a counterexample to this conjecture. This example is just the Hirzebruch
Finding feasible abstract counterexamples
 STTT
, 2003
"... Abstract. A strength of model checking is its ability to automate the detection of subtle system errors and produce traces that exhibit those errors. Given the highcomputational cost of model checking most researchers advocate the use of aggressive propertypreserving abstractions. Unfortunately, th ..."
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Cited by 23 (4 self)
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and hence worth developer time to analyze. We have explored several strategies for addressing this problem by extending an explicitstate model checker, Java PathFinder (JPF), to search for and analyze counterexamples in the presence of abstractions. We demonstrate that these techniques effectively
Folk Theorems on Transmission Access: Proofs and Counterexamples
 Journal of Regulatory Economics
, 1995
"... Nodal prices, congestion revenues, transmission capacity rights, and compensation for wire ownership are key concepts used to formulate claims about proposals to organize competitive and open transmission access. Underlying those claims are implicit assertions (folk theorems) concerning the regul ..."
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Cited by 50 (2 self)
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the regulation of transmission access, the determination of power flows, properties of economic dispatch, and the operations of competitive nodal markets for power. The paper has two objectives. We first formulate these folk theorems as explicit mathematical assertions. We then prove that some
The Pointer Assertion Logic Engine
 Proc. ACM PLDI
, 2001
"... We present a new framework for verifying partial specifications of programs in order to catch type and memory errors and check data structure invariants. Our technique can verify a large class of data structures, namely all those that can be expressed as graph types. Earlier versions were restricted ..."
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Cited by 156 (3 self)
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in the logical tradition by encoding the programs and partial specifications as formulas in monadic secondorder logic. Validity of these formulas is checked by the MONA tool, which also can provide explicit counterexamples to invalid formulas. To make verification decidable, the technique requires explicit loop
Examples and counterexamples for the Perles' conjecture
, 2000
"... The combinatorial structure of a ddimensional simple convex polytope  as given, for example, by the set of the (d 1)regular subgraphs of the facets  can be reconstructed from its abstract graph. However, no polynomial/efficient algorithm is known for this task, although a polynomially check ..."
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Cited by 7 (3 self)
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of the (simplicial) dual polytope P contains a 2complex without a free edge, and without 2dimensional homology. Examples of such complexes are known; we use a modification of "Bing's house" (two walls removed) to construct explicit 4dimensional counterexamples to the Perles conjecture.
Another counterexample to a conjecture of Zassenhaus
 BEITRÄGE ALGEBRA GEOM
, 2002
"... A metabelian group G of order 1440 is constructed which provides a counterexample to a conjecture of Zassenhaus on automorphisms of integral group rings. The group is constructed in the spirit of [8]. An augmented automorphism of ZG which has no Zassenhaus factorization is given explicitly (this wa ..."
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Cited by 1 (1 self)
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A metabelian group G of order 1440 is constructed which provides a counterexample to a conjecture of Zassenhaus on automorphisms of integral group rings. The group is constructed in the spirit of [8]. An augmented automorphism of ZG which has no Zassenhaus factorization is given explicitly (this
A Counterexample to a Conjecture of Gurvits 1 on Switched Systems
"... We consider products of matrix exponentials under the assumption that the matrices span a nilpotent Lie algebra. In 1995, Leonid Gurvits conjectured that nilpotency implies that these products are, in some sense, simple. More precisely, there exists a uniform bound l such that any product can be rep ..."
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an explicit counterexample. Yet, the underlying philosophy behind Gurvits ’ conjecture is valid in the case of thirdorder nilpotency. Namely, such systems do satisfy the following nice reachability property: any point in the reachable set can be reached using a piecewise constant control with no more than
Finding Feasible Counterexamples when Model Checking Abstracted Java Programs
 IN PROCEEDINGS OF TACAS
, 2001
"... Despite recent advances in model checking and in adapting model checking techniques to software, the state explosion problem remains a major hurdle in applying model checking to software. Recent work in automated program abstraction has shown promise as a means of scaling model checking to larg ..."
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Cited by 49 (5 self)
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the specification may be violated on a behavior in the abstracted program which is not present in the original program. We have extended an explicitstate model checker, Java PathFinder (JPF), to analyze counterexamples in the presence of abstractions. We enhanced JPF to search for "feasible" counterexamples
Counterexamples for Model Checking of Markov Decision Processes
"... Abstract. The debugging of stochastic system models relies on the availability of diagnostic information. Classic probabilistic model checkers, which are based on iterated numerical probability matrix operations, do not provide such diagnostic information. In precursory work, we have devised counter ..."
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Cited by 17 (5 self)
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counterexample generation methods for continuous and discretetime Markov Chains based on heuristics guided explicit state space search. In this paper we address the problem of generating diagnostic information, or counterexamples, for Markov Decision Processes (MDPs), which are a convenient formalism
Results 11  20
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310