Paradox literature is emerging as one of the most vital streams in management studies, but it is affected by some growing pains. First, the concept of paradox is still too fuzzy, which impacts ...empirical research and hinders communication with other literatures. Second, the assumption that paradoxes are always best met with acceptance and search for balance is problematic because it limits the heuristic potential of a paradox lens, because it constrains the range of sustainable responses to contradictions, and because it may induce to appeasement in face of injustice. In this paper we propose to strengthen paradox theory by incorporating the contributions of two alternative perspectives on organizational tensions: trade‐offs and dialectics. We thus present a model which expands organizational paradox theory by: (1) clarifying the concept of organizational paradox; and (2) offering a model that better describes the varied phenomenology, causes and consequences of organizational tensions and paradoxes.
Проблемы укладки домино являются удобным инструментом оценки алгоритмической сложности задач, возникающих в различных разделах математики, в том числе в логике. В работе описывается моделирование ...проблем домино с помощью средств языка логики предикатов, а также с помощью некоторых дополнительных средств, в том числе не выразимых элементарно. Это дает возможность получить как простые доказательства уже известных фактов о неразрешимости проблемы выполнимости формул различных фрагментов логики предикатов, так и некоторые новые результаты. Так, известно, что проблема выполнимости формул логики предикатов, содержащих не более двух предметных переменных, алгоритмически разрешима; известно также, что свойство транзитивности бинарного отношения и операция композиции двух бинарных отношений могут быть выражены в языке первого порядка с использованием трех переменных. В работе показано, что если добавить к языку первого порядка оператор проверки транзитивности бинарного отношения (или более сильное средство – оператор транзитивного замыкания) и оператор композиции, то получим язык с сильно неразрешимой проблемой выполнимости формул от двух переменных, построенных в сигнатуре с одной бинарной предикатной буквой и равенством.
We present a construction to simulate Turing machines with 3×3 matrices over rationals. The correctness of simulation is guaranteed by testing that the matrices have integral elements during the ...simulation. This construction implies an undecidability result for a special identity problem for semigroups of 3×3-matrices.
•Direct simulation of a Turing machine with 3 × 3 rational matrices with integrality test.•The elements of the matrices in the simulation are significantly smaller than in the classical simulations using the PCP.•Undecidability of the Identity matrix problem in a special case for 3 × 3 rational matrices.
Most Tensor Problems Are NP-Hard HILLAR, Christopher J; LIM, Lek-Heng
Journal of the ACM,
11/2013, Letnik:
60, Številka:
6
Journal Article
Recenzirano
Odprti dostop
We prove that multilinear (tensor) analogues of many efficiently computable problems in numerical linear algebra are NP-hard. Our list includes: determining the feasibility of a system of bilinear ...equations, deciding whether a 3-tensor possesses a given eigenvalue, singular value, or spectral norm; approximating an eigenvalue, eigenvector, singular vector, or the spectral norm; and determining the rank or best rank-1 approximation of a 3-tensor. Furthermore, we show that restricting these problems to symmetric tensors does not alleviate their NP-hardness. We also explain how deciding nonnegative definiteness of a symmetric 4-tensor is NP-hard and how computing the combinatorial hyperdeterminant is NP-, #P-, and VNP-hard.
Text as haunt Washbourne, Kelly; Cruz-Martes, Camelly
Translation and interpreting studies,
5/2024, Letnik:
19, Številka:
1
Journal Article
Recenzirano
Abstract The spectral in translation may be considered an opportunity for opening, and the textual haunting that results, a way of conceiving of other-inhabitedness. Texts, translations, authors and ...translators have long been framed in the discourse of hauntedness as a way of coming to terms with their complex subjectivities. A hauntological approach to translation allows for an engagement with the presence-in-absence of a ‘source,’ the translational disjunctures of time and space, the return of the traumatic and the repressed, and the promise of alterity. We posit three potential components of translational spectrality: (1) translation and trauma; (2) haunted texts and readings, including acts of translation; and (3) the spectral author and translator. The figure of the ghost confronts that of the autonomous author, at the same time giving voice to the (dis)embodied translator and attendant invisibilities of their status.
We consider Presburger arithmetic extended by the sine function, call this extension sine-Presburger arithmetic (sin-PA), and systematically study decision problems for sets of sentences in sin-PA. ...In particular, we detail a decision algorithm for existential sin-PA sentences under assumption of Schanuel's conjecture. This procedure reduces decisions to the theory of the ordered additive group of real numbers extended by sine, which is decidable under Schanuel's conjecture. On the other hand, we prove that four alternating quantifier blocks suffice for undecidability of sin-PA sentences. To do so, we explicitly interpret the weak monadic second-order theory of the grid, which is undecidable, in sin-PA.
Session types are behavioural types for guaranteeing that concurrent programs are free from basic communication errors. Recent work has shown that asynchronous session subtyping is undecidable. ...However, since session types have become popular in mainstream programming languages in which asynchronous communication is the norm rather than the exception, it is crucial to detect significant decidable subtyping relations. Previous work considered extremely restrictive fragments in which limitations were imposed to the size of communication buffer (at most 1) or to the possibility to express multiple choices (disallowing them completely in one of the compared types). In this work, for the first time, we show decidability of a fragment that does not impose any limitation on communication buffers and allows both the compared types to include multiple choices for either input or output, thus yielding a fragment which is more significant from an applicability viewpoint. In general, we study the boundary between decidability and undecidability by considering several fragments of subtyping. Notably, we show that subtyping remains undecidable even if restricted to not using output covariance and input contravariance.
In 1 we construct aperiodic tile sets on the Baumslag-Solitar groups BS(m,n). Aperiodicity plays a central role in the undecidability of the classical domino problem on Z2, and analogously to this we ...state as a corollary of the main construction that the Domino problem is undecidable on all Baumslag-Solitar groups. In the present work we elaborate on the claim and provide a full proof of this fact. We also provide details of another result reported in 1: there are tiles that tile the Baumslag-Solitar group BS(m,n) but none of the valid tilings is recursive. The proofs are based on simulating piecewise affine functions by tiles on BS(m,n).
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