This article evaluates each of the reactions known to be involved in visual transduction as a potential site for the regulation of light adaptation. Extensive evidence suggests that calcium acts as a feedback messenger at several different points and recent work suggests a role for cGMP in regulating the primary excitatory pathway. A conclusion is that adaptation is likely to be regulated by multiple and redundant mechanisms. The goal of future experimentation will be to determine the relative importance of each (...) of these. (shrink)

Streamer F mutants have been found to be useful tools for studying the pathway of signal transduction leading to chemotactic cell movement. The primary defect in these mutants is in the structural gene for the cyclic GMP specific phosphodiesterase. This defect allows a larger and prolonged peak of cyclic GMP to be formed in response to the chemotactic stimulus, cyclic AMP. This characteristic aberrant pattern of cyclic GMP accumulation in the streamer F mutants has been (...) correlated with similar patterns of changes in the influx of calcium from the medium, myosin II association with the cytoskeleton, myosin phosphorylation and a decrease in speed of movement of the amoebae. From these studies a sequence of events can be deduced that leads from cell surface cyclic AMP stimulation to cell polarization prior to movement of the amoebae in response to the chemotactic stimulus. (shrink)

Cyclic nucleotides can regulate the sensitivity of retinal rods to light through phosducin. The phosphorylation state of phosducin determines the amount of G available for activation by Rho*. Phosducin phosphorylation is regulated by cyclic nucleotides through their activation of cAMP-dependent protein kinase. The regulation of phosphodiesterase activity by the noncatalytic cGMP binding sites as well as Ca2+/calmodulin dependent regulation of cGMP binding to the cation channel are also discussed.

The cyclic GMP‐AMP synthase–stimulator of interferon genes (cGAS‐STING) pathway is central for the initiation of anti‐tumoural immune responses. Enormous effort has been made to optimise the design and administration of STING agonists to stimulate tumour immunogenicity. However, in certain contexts the cGAS‐STING axis fuels tumourigenesis. Here, we review recent findings on the regulation of cGAS expression and activity. We particularly focus our attention on the DNA‐dependent protein kinase (DNA‐PK) complex, that recently emerged as an activator of inflammatory responses in (...) tumour cells. We propose that stratification analyses on cGAS and DNA‐PK expression/activation status should be carried out to predict treatment efficacy. We herein also provide insights into non‐canonical functions borne by cGAS and cGAMP, highlighting how they may influence tumourigenesis. All these parameters should be taken into consideration concertedly to choose strategies aiming to effectively boost tumour immunogenicity. (shrink)

The cyclic GMP-gated channel responds to changes in free intracellular cGMP, and as a result, it plays a central role in the phototransduction process in rod and cone photoreceptor cells. Recent biochemical, immunochemical, and molecular biology studies indicate that this channel consists of a complex of two distinct subunits and one or more associated proteins. Primary structural analysis indicates that the a and (3 subunits contain a cGMP-binding domain, an even number of membrane-spanning segments, a voltage sensor motif and (...) a pore region. The latter two features are found in voltage-gated channels and suggest that these two classes of channels have evolved from the same ancestral channel protein. A working model for the membrane topography of the channel subunits is proposed based on immunogold labeling studies and sequence analysis. Recent studies also indicate that calmodulin binds to the 240 kDa protein of the channel complex and modulates the sensitivity of the channel for cGMP in a Ca2+-dependent manner. The molecular properties of the channel complex and the possible role of Ca2+-calmodulin modulation of the channel during photoactivation and photorecovery are discussed in relation to the current mechanism of phototransduction in photoreceptor cells. (shrink)

The second messenger molecules cAMP and Ca2+ regulate a large number of eukaryotic cellular events. cAMP acts on protein kinases and Ca2+ works through a ubiquitous calcium‐binding protein, calmodulin. The two systems are not independent, however, but interact in several important fashions. These interactions, and, in particular, the modulation of the cAMP signal by two Ca2+/calmodulin‐regulated proteins, cyclic nucleotide phosphodiesterase and calcineurin, are described here.

Recoverin is a 23 kDa Ca2+binding protein that has been detected primarily in vertebrate photoreceptors. The role of recoverin in phototransduction has been investigated using a variety of biochemical methods. Initial reports suggesting that recoverin regulates photoreceptor guanylyl cyclase have not been confirmed. Instead, recoverin appears to determine the lifetime of lightstimulated phosphodiesterase activity, perhaps by regulating rhodopsin phosphorylation. Retinal recoverin is heterogeneously fatty acylated at its ammo-terminus. The amino-terminal fatty acid appears to be involved in the interaction of (...) recoverin with photoreceptor membranes. (shrink)

During the formation of the brain, neuronal cell migration and neurite extension are controlled by extracellular guidance cues. Here, I discuss experiments showing that the messenger nitric oxide (NO) is an additional regulator of cell motility. NO is a membrane permeant molecule, which activates soluble guanylyl cyclase (sGC) and leads to the formation of cyclic GMP (cGMP) in target cells. The analysis of specific cells types in invertebrate models such as molluscs, insects and the medicinal leech provides insight how (...) NO and cyclic nucleotides affect the wiring of nervous systems by regulating cell and growth‐cone motility. Inhibition of the NOS and sGC enzymes combined with rescue experiments show that NO signalling orchestrates neurite outgrowth and filopodial dynamics, cell migration of enteric neurons, glial migration and axonogenesis of pioneer fibers. Cultured insect embryos are accessible model systems in which cellular mechanisms of NO‐induced cytoskeletal reorganizations can be analyzed in natural settings. Finally, I will outline some indications that NO may also regulate cell motility in the developing and regenerating vertebrate nervous system. BioEssays 27:495–505, 2005. © 2005 Wiley Periodicals, Inc. (shrink)

The life cycle of Dictyostelium discoideum offers a unique opportunity to study signal transduction in eukaryotic cells at both the unicellular and multicellular levels of organization. Adding to the already extensive knowledge of the unicellular stages, classical and molecular genetics have begun to unravel transduction of signals controlling morphogenesis and behaviour (phototaxis and thermotaxis) in the multicellular ‘slug’ stage of the life cycle. Distributed over all seven genetic linkage groups are probably about 20, but possibly as many as 55, genes (...) of importance for slug behaviour. The encoded proteins appear from pharmacological studies and mutant phenotypes to govern transduction pathways involving the intracellular second messengers cyclic AMP, cyclic GMP, IP3 and Ca2+. Pathways from the photo‐ and thermoreceptors converge first with each other and thence, at the level of the second messengers, with those from extracellular tip activation (cyclic AMP) and inhibition (Slug Turning Factor and/or ammonia and/or adenosine) signals that control slug movement and morphogenesis. (shrink)

Atrial natriuretic peptides appear to elicit their actions in some target tissues by binding to a novel cell‐surface transmembrane protein which possesses both peptide binding and guanylate cyclase activities. Ligand binding stimulates enzyme activity to produce increased intracellular concentrations of cyclic GMP which, in turn, mediates the cell's physiological response.

This commentary discusses the balance of phosphodiesterase and guanylate cyclase activities in vertebrate photoreceptors at moderate light intensities. The rate of cGMP hydrolysis and synthesis seem to equal each other. Ca2+as regulator of both enzyme activities is also effectively buffered in photoreceptor cells by cytoplasmic buffer components.

In the current model of visual transduction, the lifetime of active cGMP phosphodiesterase depends upon the period of its interaction with GTP-bound transducin. If recoverin regulates the lifetime of light-activated cGMP phosphodiesterase through inhibition of rhodopsin phosphorylation, rhodopsin should directly interact with cGMP phosphodiesterase and/or GTP-bound transducin complexed with cGMP phosphodiesterase. Is this true?

Cyclic mechanic is intended as a suitable generalization both of quantum mechanics and general relativity apt to unify them. It is founded on a few principles, which can be enumerated approximately as follows: 1. Actual infinity or the universe can be considered as a physical and experimentally verifiable entity. It allows of mechanical motion to exist. 2. A new law of conservation has to be involved to generalize and comprise the separate laws of conservation of classical and relativistic mechanics, (...) and especially that of conservation of energy: This is the conservation of action or information. 3. Time is not a uniformly flowing time in general. It can have some speed, acceleration, more than one dimension, to be discrete. 4. The following principle of cyclicity: The universe returns in any point of it. The return can be only kinematic, i.e. per a unit of energy (or mass), and thermodynamic, i.e. considering the universe as a thermodynamic whole. 5. The kinematic return, which is per a unit of energy (or mass), is the counterpart of conservation of energy, which can be interpreted as the particular case of conservation of action “per a unit of time”. The kinematic return per a unit of energy (or mass) can be interpreted in turn as another particular law of conservation in the framework of conservation of action (or information), namely conservation of wave period (or time). These two counterpart laws of conservation correspond exactly to the particle “half” and to the wave “half” of wave-particle duality. 6. The principle of quantum invariance is introduced. It means that all physical laws have to be invariant to discrete and continuous (smooth) morphisms (motions) or mathematically, to the axiom of choice. The list is not intended to be exhausted or disjunctive, but only to give an introductory idea. (shrink)

Probably many people have cyclic preferences: they prefer A to B, B to C and C to A for some objects of choice A, B and C. Recent work has resurrected the objection to cyclic preference that agents possessing them are open to exploitation by means of ‘money pumps’. The paper briefly reviews this work and proposes a general approach to problems of sequential choice that makes cyclic preference immune to exploitation by means of these new mechanisms.

In this paper we characterize the MV-algebras containing as subalgebras Post algebras of finitely many orders. For this we study cyclic elements in MV-algebras which are the generators of the fundamental chain of the Post algebras.

We introduce a path-based cyclic proof system for first-order $\mu $-calculus, the extension of first-order logic by second-order quantifiers for least and greatest fixed points of definable monotone functions. We prove soundness of the system and demonstrate it to be as expressive as the known trace-based cyclic systems of Dam and Sprenger. Furthermore, we establish cut-free completeness of our system for the fragment corresponding to the modal $\mu $-calculus.

This paper proposes an architecture for the mapping between syntax and phonology — in particular, that aspect of phonology that determines ordering. In Fox and Pesetsky (in prep.), we will argue that this architecture, when combined with a general theory of syntactic domains ("phases"), provides a new understanding of a variety of phenomena that have received diverse accounts in the literature. This shorter paper focuses on two processes, both drawn from Scandinavian: the familiar process of Object Shift and the less (...) well-known process of Quantifier Movement. We will argue that constraints on these operations can be seen as instances of the same property of grammar that explains the fact that movement is local and successive cyclic. We begin by sketching a model in which locality and successive cyclicity are consequences of the architecture that we propose, rather than specific facts about movement itself. We next present our proposal in somewhat greater detail, and show how it can account for a wide range of apparent limitations on movement — in particular, superficially contradictory restrictions on Object Shift and Quantifier Movement. The restrictions on Object Shift include those grouped under the rubric of Holmberg's Generalization, which Quantifier Movement does not seem to obey. We will argue that Quantifier Movement instead obeys a near mirror-image of Holmberg's Generalization (an "Inverse Holmberg Effect"), but that both Holmberg's Generalization and its mirror image are expected if our proposed architecture is correct. (shrink)

Many causal systems studied by sciences such as biology, pharmacology, and economics feature causal cycles. Most accounts of causal modelling currently on the market are, however, explicitly designed to study acyclic structures. This chapter focuses on causal cycles and the challenges such cycles pose for causal modelling. First, we distinguish between different types of causal cycles. Then we introduce causal models and discuss a selection of general challenges for cyclic models when it comes to representation, prediction, and causal discovery. (...) Finally, we zoom in on a concrete case from biochemistry: the PI3K/mTOR signalling network that plays a crucial role in regulating the cell cycle. Using this case we discuss some possible pitfalls for the application of causal modelling tools to complex biological cases. (shrink)

More than a decade of experimental research confirms that external linguistic information provided in the form of word labels can induce a "mutually exclusive" bias against double naming and lead children to infer the name of novel objects and parts. Linguistic labels have also been shown to encourage more sophisticated reasoning, particularly with respect to superordinate and atypical object categorization. By contrast, however, the inverse possibility that the linguistic labeling of basic-level objects may also developmentally support the kind of "phonological (...) reorganization" observed within infant speech categorization has yet to be theoretically isolated and experimentally explored. Yet the dynamic of relying on labels to inform object categorization clearly presupposes that potential word labels themselves have already been classified into language-specific phonemic categories. However, a two-staged strategy of first relying on basic-level object categories to refine speech categorization, and then exploiting such learned speech categories to fine tune object categorization would reveal a cyclically opportunistic learner. A uniform assumption of a one to one pairing between words and objects allows bootstrapping not only from language to object classification, but also from basic object categorization to phonemic speech classification. (shrink)

Many models of evolution are implicitly causal processes. Features such as causal feedback between evolutionary variables and evolutionary processes acting at multiple levels, though, mean that conventional causal models miss important phenomena. We develop here a general theoretical framework for analyzing evolutionary processes drawing on recent approaches to causal modeling developed in the machine-learning literature, which have extended Pearls do-calculus to incorporate cyclic causal interactions and multilevel causation. We also develop information-theoretic notions necessary to analyze causal information dynamics in (...) our framework, introducing a causal generalization of the Partial Information Decomposition framework. We show how our causal framework helps to clarify conceptual issues in the contexts of complex trait analysis and cancer genetics, including assigning variation in an observed trait to genetic, epigenetic and environmental sources in the presence of epigenetic and environmental feedback processes, and variation in fitness to mutation processes in cancer using a multilevel causal model respectively, as well as relating causally-induced to observed variation in these variables via information theoretic bounds. In the process, we introduce a general class of multilevel causal evolutionary processes which connect evolutionary processes at multiple levels via coarse-graining relationships. Further, we show how a range of fitness models can be formulated in our framework, as well as a causal analog of Prices equation, clarifying the relationships between realized/probabilistic fitness and direct/indirect selection. Finally, we consider the potential relevance of our framework to foundational issues in biology and evolution, including supervenience, multilevel selection and individuality. Particularly, we argue that our class of multilevel causal evolutionary processes, in conjunction with a minimum description length principle, provides a conceptual framework in which identification of multiple levels of selection may be reduced to a model selection problem. (shrink)

The jaw movements of speech are most probably derived from jaw movements associated with vocalisation. Cyclicity does not argue strongly for derivation from a cyclic pattern, because it arises readily in any system with feedback control. The appearance of regular repetition as a part of ritualisation of a display may have been important.

Guns, slug-throwing weapons, have evolved as humans have increased their grasp of the mechanical arts. In the near future, however, it seems likely that soldiers' rifles operating at punishing cyclic rates of fire face the limits of physics and materials science— heat and speed will cost accuracy and distance. This article considers not only the near future of the personal weapon carried by soldiers in battlespace but also the rifle's evolution as an index of alterations in 20th-and 21st-century war (...) fighting. The arc traced by multiple-fire weapons, from the Gatling to the laser rifle, is a narrative of humans, machinery, and their cocreative symbiotic relationship. This article begins by examining some current examples of late-generation rifles and their imagined futures, continues by pursuing the linkages between guns and soldiers, and finally asks what new guns will mean for soldiers being born now. (shrink)

This paper proposes an architecture for the mapping between syntax and phonology — in particular, that aspect of phonology that determines ordering. In Fox and Pesetsky (in prep.), we will argue that this architecture, when combined with a general theory of syntactic domains ("phases"), provides a new understanding of a variety of phenomena that have received diverse accounts in the literature. This shorter paper focuses on two processes, both drawn from Scandinavian: the familiar process of Object Shift and the less (...) well-known process of Quantifier Movement. We will argue that constraints on these operations can be seen as instances of the same property of grammar that explains the fact that movement is local and successive cyclic. We begin by sketching a model in which locality and successive cyclicity are consequences of the architecture that we propose, rather than specific facts about movement itself. We next present our proposal in somewhat greater detail, and show how it can account for a wide range of apparent limitations on movement — in particular, superficially contradictory restrictions on Object Shift and Quantifier Movement. The restrictions on Object Shift include those grouped under the rubric of Holmberg's Generalization, which Quantifier Movement does not seem to obey. We will argue that Quantifier Movement instead obeys a near mirror-image of Holmberg's Generalization (an "Inverse Holmberg Effect"), but that both Holmberg's Generalization and its mirror image are expected if our proposed architecture is correct. (shrink)

In the post-Soviet context, various cyclical models of recurrent Russian “Times of Troubles” have become increasingly popular. This perspective emerged first in Soviet dissident circles, who used it as a means to expose as mistaken the Soviet belief in continual historical progress on Russian soil. In post-Soviet Russia this critical approach has been continued by members of the “Akhezier circle,” the economist Egor Gaidar, and others. Meanwhile it was given an affirmative, conservative reinterpretation by Aleksandr Panarin, according to whom Russia (...) has always managed to overcome its phases of devastating Westernization and state collapse. This idea of Russian history has become influential; even Vladimir Putin has talked about Russia as a strong state able to survive various “Times of Troubles” from the early seventeenth century to the early post-Soviet period. It also figures prominently among members of the neoconservative Izborsk Club. This article analyzes different conceptions of Russian history as cyclical and their prominent place in the prevailing civilizational discourse of post-Soviet Russia. By means of postcolonial perspectives, this discourse is seen on the one hand as an attempt to question and reject Western hegemony, attempts that on the other hand nevertheless seem unable to liberate themselves from a normative dependence on the West. (shrink)

Recursive linear structural equation models can be represented by directed acyclic graphs. When represented in this way, they satisfy the Markov Condition. Hence it is possible to use the graphical d-separation to determine what conditional independence relations are entailed by a given linear structural equation model. I prove in this paper that it is also possible to use the graphical d-separation applied to a cyclic graph to determine what conditional independence relations are entailed to hold by a given non-recursive (...) linear structural equation model. I also give a causal intepretation to the linear coefficients in a non- recursive structural equation models, and explore the relationships between cyclic graphs and undirected graphs, directed acyclic graphs with latent variables, and chain independence graphs. (shrink)

Penrose's conformal cyclic cosmology describes the cosmos as a collection of successive universes, the so-called aeons. The beginning and ending of our universe are directly connected to two other, anterior and posterior, universes. Penrose considers but rules out a different interpretation of conformal cyclic cosmology: that the beginning of our universe is connected to its own end in a cosmic loop. The paper argues that the view, aeon monism, should be regarded as a natural interpretation of conformal (...) class='Hi'>cyclic cosmology and discusses its implications for the concept of eternal return in light of the most popular metaphysics of time. (shrink)

The dynamics inherent to the life activity of all living systems presents itself in the form of regular patterns viewed by the observer as taking place in an extended timeline. Routines, rituals and celebrations, each in their own way, are defined by the typical cyclical behavioural patterns exhibited by individuals embedded in specific semiospheres. The particular nature of these semiospheres will determine the distinct patterns of behaviour to be adopted in different life contexts so that existential functions are fulfilled. The (...) restricted and protected family circle normally provides the initial learning environment where the definition of the individual’s Umwelt (von Uexküll 1909, 1934; Ferreira, Biosemiotics 3(1):107–130, 2010, 2011) his/her meaningful world, starts to take shape. This learning process comprehends the progressive identification of distinct physical entities, the development of basic patterns of physical and social behaviour- the incorporation of basic routines and the assignment of meaning to particular events. (shrink)

In 1976, the Genetics Society of America published a document entitled “Resolution of Genetics, Race, and Intelligence.” This document laid out the Society’s position in the IQ controversy, particularly that on scientific and ethical questions involving the genetics of intellectual differences between human populations. Since the GSA was the largest scientific society of geneticists in the world, many expected the document to be of central importance in settling the controversy. Unfortunately, the Resolution had surprisingly little influence on the discussion. In (...) 1979, William Provine analyzed the possible factors that decreased the impact of the Resolution, among them scientists’ limited understanding of the relationship between science and ethics. Through the analysis of unpublished versions of the Resolution and exchanges between GSA members, I will suggest that the limited impact of the statement likely depended on a shift in the aims of the GSA due to the controversies that surrounded the preparation of the document. Indeed, the demands of the membership made it progressively more impartial in both scientific and political terms, decreasing its potential significance for a wider audience. Notably, the troubled history of the Resolution raises the question of what can make effective or ineffective the communication between scientists and the public—a question with resonance in past and present discussions on topics of social importance. (shrink)

It is well known that in Sluicing constructions wh-dependencies can cross certain projections that are otherwise barriers to movement (Ross (1969), Chomsky (1972)). This fact would follow under the assumption that the relevant barriers are somehow deactivated when phonologically deleted ('island repair'). The problem, however, is that another form of phonological deletion (VP Ellipsis, VPE) seems to be impossible in certain contexts where Sluicing allows for island repair (Chung et al. (1995), Merchant (1999)).

Our synthetic review of the relevant and related literatures on the ethics and effects of using AI in education reveals five qualitatively distinct and interrelated divides associated with access, representation, algorithms, interpretations, and citizenship. We open our analysis by probing the ethical effects of algorithms and how teams of humans can plan for and mitigate bias when using AI tools and techniques to model and inform instructional decisions and predict learning outcomes. We then analyze the upstream divides that feed into (...) and fuel the algorithmic divide, first investigating access and then representation. After that, we analyze the divides that are downstream of the algorithmic divide associated with interpretation and citizenship. At present, lacking ongoing reflection and action by learners, educators, educational leaders, designers, scholars, and policymakers, the five divides collectively create a vicious cycle and perpetuate structural biases in teaching and learning. However, increasing human responsibility and control over these divides can create a virtuous cycle that improves diversity, equity, and inclusion in education. We conclude the article by looking forward and discussing ways to increase educational opportunity and effectiveness for all by mitigating bias through a cycle of progressive improvement. (shrink)

An example shows that 'pairwise preferences' (certain hypothetical choices) can cycle even when rational. General considerations entail that preferences tout court (certain relations of actual valuations) cannot cycle. A world-bayesian theory is explained that accommodates these two kinds of preference, and a theory for rational actions that would have them maximize and be objects of ratifiable choices. It is observed that choices can be unratifiable either because of troublesome credences or because of troublesome preferences. An appendix comments on a third (...) way in which efforts to maximize can be frustrated. (shrink)

To formally understand cyclicity in innovation and to tie to Schumpeter’s idea about waves of creative destruction, we elaborate upon Thomas Kuhn’s (1962) hypothesis that science evolves through a succession of paradigm life cycles by noting that entrepreneurs recognize the profitability of new scientific theories through a delay. The delay from innovation to entrepreneurship may be due to technological inertia, the time taken in recognizing the applications of basic research, or related to how quickly technological change evolves over time and (...) its returns are realized. In our model, a profit-maximizing entrepreneur uses the latest scientific knowledge to create innovative technologies, which generates cycles between science and innovation. The necessary conditions for the existence of cycles are that human capital employed in science creation and high valued innovations is high, and the interest rate is low. The findings also tie to the notion about the variability of innovation over the business cycle and can provide useful inputs into the formulation of more effective technology policies. (shrink)

Nikolay Kondratieff is known primarily for his theory of long cycles. However, it is worth recalling that he was among the first who started to investigate the nature of different economic cycles and their systematic interaction. Actually the primary classification of cycles into short, medium and long belongs to Kondratieff.

Relativistic models of an expanding universe followed by contraction, or a big bang followed by a big crunch, were first proposed by A. Friedmann in 1922 and nine years later by A. Einstein. In the period ca. 1922–1960, the more speculative idea of a large and possibly infinite number of cycles was discussed by R. Tolman in particular. To some cosmologists, the idea was philosophically appealing because it seemed to justify an eternal yet dynamic universe without an absolute beginning in (...) time. During the 1950s models of this kind, sometimes known as Phoenix models, were investigated by a few cosmologists of whom the most important were A. Dauvillier, W. Bonnor, and H. Zanstra. (shrink)

Women’s preferences for several male traits, including voices, change over the menstrual cycle, but the proximate causes of these changes are unknown. This paper explores relationships between levels of estradiol, progesterone, luteinizing hormone, follicle stimulating hormone, prolactin, and testosterone (estimated using menstrual cycle information) and women’s preferences for male vocal masculinity in normally cycling and hormonally contracepting heterosexual females. Preferences for vocal masculinity decreased with predicted progesterone levels and increased with predicted prolactin levels in normally cycling—but not hormonally contracepting—women. Adaptive (...) explanations for menstrual variation in women’s preferences for masculine traits are discussed and evaluated in light of these findings. (shrink)

In the context of solving large distributed constraint optimization problems, belief-propagation and incomplete inference algorithms are candidates of choice. However, in general, when the problem structure is very cyclic, these solution methods suffer from bad performance, due to non-convergence and many exchanged messages. As to improve performances of the MaxSum inference algorithm when solving cyclic constraint optimization problems, we propose here to take inspiration from the belief-propagation-guided decimation used to solve sparse random graphs. We propose the novel DeciMaxSum (...) method, which is parameterized in terms of policies to decide when to trigger decimation, which variables to decimate and which values to assign to decimated variables. Based on an empirical evaluation on a classical constraint optimization benchmarks, some of these combinations of policies, using periodic decimation, cycle detection-based decimation, parallel and non parallel decimation, random or deterministic variable selection and deterministic or random sampling for value selection, outperform state-of-the-art competitors in many settings. (shrink)

• Why does wh-movement proceed through the left edge of CP? • Logic of a common answer: Things would go wrong otherwise.