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  • Publication . Other literature type . Article . Preprint . 2016 . Embargo End Date: 01 Jan 2016
    Open Access English
    Authors: 
    Plonka, A.I.; Blom, N.A.; Fichtner, A.; Seismology; NWO-VIDI: Full waveform inversion for upper-mantle density structure;
    Publisher: ETH Zurich
    Countries: Switzerland, Netherlands
    Project: NWO | Full waveform inversion f... (2300172344)

    Density heterogeneities are the source of mass transport in the Earth. However, the 3-D density structure remains poorly constrained because travel times of seismic waves are only weakly sensitive to density. Inspired by recent developments in seismic waveform tomography, we investigate whether the visibility of 3-D density heterogeneities may be improved by inverting not only travel times of specific seismic phases but complete seismograms. As a first step in this direction, we perform numerical experiments to estimate the effect of 3-D crustal density heterogeneities on regional seismic wave propagation. While a finite number of numerical experiments may not capture the full range of possible scenarios, our results still indicate that realistic crustal density variations may lead to travel-time shifts of up to ∼ 1s and amplitude variations of several tens of percent over propagation distances of ∼ 1000km. Both amplitude and travel-time variations increase with increasing epicentral distance and increasing medium complexity, i.e. decreasing correlation length of the heterogeneities. They are practically negligible when the correlation length of the heterogeneities is much larger than the wavelength. However, when the correlation length approaches the wavelength, density-induced waveform perturbations become prominent. Recent regional-scale full-waveform inversions that resolve structure at the scale of a wavelength already reach this regime. Our numerical experiments suggest that waveform perturbations induced by realistic crustal density variations can be observed in high-quality regional seismic data. While density-induced travel-time differences will often be small, amplitude variations exceeding ±10% are comparable to those induced by 3-D velocity structure and attenuation. While these results certainly encourage more research on the development of 3-D density tomography, they also suggest that current full-waveform inversions that use amplitude information may be biased due to the neglect of 3-D variations in density. Solid Earth, 7 (6) ISSN:1869-9510 ISSN:1869-9529

  • Open Access English
    Authors: 
    Nataliya M. Komarova; Olav Velthuis;
    Country: Netherlands
    Project: NWO | The Globalization of High... (2300162562)

    ABSTRACTThe paper studies how local contexts contribute to the emergence of markets. In particular, it explains how potential entrepreneurs are motivated to become active in establishing new markets. Empirically, the focus is on contemporary art markets in two emerging countries: India and Russia. The paper draws upon qualitative interviews with 65 contemporary art dealers conducted in New Delhi, Mumbai, Moscow and Saint Petersburg. We show how different socio-cultural contexts function as activation mechanisms: in India, family backgrounds predominantly structure the decision-making processes, among others through the economic, social and cultural capital which these families provide. In Russia, by contrast, such family background is non-existent. Instead, the socio-economic turmoil of 1990s and 2000s as well as the strong involvement of the state function as activation mechanisms. We suggest that these different activation mechanisms contribute to explaining the diverging market performance in both coun...

  • Open Access English
    Authors: 
    Beddow, Helen M.; Liebrand, Diederik; Wilson, Douglas S.; Hilgen, Frits J.; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.; Stratigraphy and paleontology; Marine palynology and palaeoceanography; Stratigraphy & paleontology;
    Country: Netherlands
    Project: EC | ERAS (293741), EC | EARTHSEQUENCING (617462), NWO | Evolution of astronomical... (2300157723)

    Astronomical tuning of sediment sequences requires both unambiguous cycle pattern recognition in climate proxy records and astronomical solutions, as well as independent information about the phase relationship between these two. Here we present two different astronomically tuned age models for the Oligocene–Miocene transition (OMT) from Integrated Ocean Drilling Program Site U1334 (equatorial Pacific Ocean) to assess the effect tuning has on astronomically calibrated ages and the geologic timescale. These alternative age models (roughly from ∼ 22 to ∼ 24 Ma) are based on different tunings between proxy records and eccentricity: the first age model is based on an aligning CaCO3 weight (wt%) to Earth's orbital eccentricity, and the second age model is based on a direct age calibration of benthic foraminiferal stable carbon isotope ratios (δ13C) to eccentricity. To independently test which tuned age model and associated tuning assumptions are in best agreement with independent ages based on tectonic plate-pair spreading rates, we assign the tuned ages to magnetostratigraphic reversals identified in deep-marine magnetic anomaly profiles. Subsequently, we compute tectonic plate-pair spreading rates based on the tuned ages. The resultant alternative spreading-rate histories indicate that the CaCO3 tuned age model is most consistent with a conservative assumption of constant, or linearly changing, spreading rates. The CaCO3 tuned age model thus provides robust ages and durations for polarity chrons C6Bn.1n–C7n.1r, which are not based on astronomical tuning in the latest iteration of the geologic timescale. Furthermore, it provides independent evidence that the relatively large (several 10 000 years) time lags documented in the benthic foraminiferal isotope records relative to orbital eccentricity constitute a real feature of the Oligocene–Miocene climate system and carbon cycle. The age constraints from Site U1334 thus indicate that the delayed responses of the Oligocene–Miocene climate–cryosphere system and (marine) carbon cycle resulted from highly non-linear feedbacks to astronomical forcing.

  • Publication . Article . 2009
    Open Access English
    Authors: 
    Galit W. Sassoon;
    Country: Netherlands
    Project: NWO | Modeling the role of vagu... (2300152423)

    This paper presents a novel semantic analysis of unit names (like pound and meter) and gradable adjectives (like tall, short and happy), inspired by measurement theory (Krantz et al. In Foundations of measurement: Additive and Polynomial Representations, 1971). Based on measurement theory’s four-way typology of measures, I claim that different adjectives are associated with different types of measures whose special characteristics, together with features of the relations denoted by unit names, explain the puzzling limited distribution of measure phrases, as well as unit-based comparisons between predicates (as in the table is longer than it is wide). All considered, my analyses support the view that the grammar of natural languages is sensitive to features of measurement theory.

  • Open Access
    Authors: 
    P. Marcos Crichigno; Takuya Matsumoto; Kentaroh Yoshida;
    Publisher: IOP Publishing
    Project: NWO | Geometrical aspects of su... (2300157346)

    Yang-Baxter sigma models, proposed by Klimcik and Delduc-Magro-Vicedo, have been recognized as a powerful framework for studying integrable deformations of two-dimensional non-linear sigma models. In this short article, as an important generalization, we review a non-integrable sigma model in the Yang-Baxter sigma model approach based on [arXiv:1406.2249]. In particular, we discuss a family of deformations of the 5D Sasaki-Einstein manifold $T^{1,1}$, instead of the standard deformations of the $5$-sphere S$^5$. For this purpose, we first describe a novel construction of $T^{1,1}$ as a supercoset, and provide a physical interpretation of this construction from viewpoint of the dual Klebanov-Witten field theory. Secondly, we consider a $3$-parameter deformation of $T^{1,1}$ by using classical $r$-matrices satisfying the classical Yang--Baxter equation (CYBE). The resulting metric and NS-NS two-form completely agree with the ones previously obtained via TsT (T-dual -- shift -- T-dual) transformations, and contain the Lunin-Maldacena background as a special case. Our result indicates that what we refer to as the gravity/CYBE(Classical Yang-Baxter Equation) correspondence can be extended beyond integrable cosets. Comment: This article is a brief review of the original paper [arXiv:1406.2249] prepared for a proceeding of a talk given by T.M. at "The XXIIIth International Conference on Integrable Systems and Quantum symmetries (ISQS-23)" held in Prague, Czech Republic, from June 23 till June 27, 2015, v2: references added

  • Publication . Preprint . Conference object . Article . 2017
    Open Access English
    Authors: 
    Fadaee, M.; Bisazza, A.; Monz, C.; Barzilay, R.; Kan, M.-Y.;
    Publisher: Association for Computational Linguistics
    Country: Netherlands
    Project: NWO | Surface Realization in St... (2300172930)

    The quality of a Neural Machine Translation system depends substantially on the availability of sizable parallel corpora. For low-resource language pairs this is not the case, resulting in poor translation quality. Inspired by work in computer vision, we propose a novel data augmentation approach that targets low-frequency words by generating new sentence pairs containing rare words in new, synthetically created contexts. Experimental results on simulated low-resource settings show that our method improves translation quality by up to 2.9 BLEU points over the baseline and up to 3.2 BLEU over back-translation. Comment: 5 pages, 2 figures, Accepted at ACL 2017

  • Open Access
    Authors: 
    Eric Bouwers; Martin Bravenboer; Eelco Visser;
    Publisher: Elsevier BV
    Project: NWO | TraCE: Capturing Timeline... (1800113975)

    AbstractA wide range of parser generators are used to generate parsers for programming languages. The grammar formalisms that come with parser generators provide different approaches for defining operator precedence. Some generators (e.g. YACC) support precedence declarations, others require the grammar to be unambiguous, thus encoding the precedence rules. Even if the grammar formalism provides precedence rules, a particular grammar might not use it. The result is grammar variants implementing the same language. For the C language, the GNU Compiler uses YACC with precedence rules, the C-Transformers uses SDF without priorities, while the SDF library does use priorities. For PHP, Zend uses YACC with precedence rules, whereas PHP-front uses SDF with priority and associativity declarations.The variance between grammars raises the question if the precedence rules of one grammar are compatible with those of another. This is usually not obvious, since some languages have complex precedence rules. Also, for some parser generators the semantics of precedence rules is defined operationally, which makes it hard to reason about their effect on the defined language. We present a method and tool for comparing the precedence rules of different grammars and parser generators. Although it is undecidable whether two grammars define the same language, this tool provides support for comparing and recovering precedence rules, which is especially useful for reliable migration of a grammar from one grammar formalism to another. We evaluate our method by the application to non-trivial mainstream programming languages, such as PHP and C.

  • Open Access
    Authors: 
    Marco Spruit;
    Publisher: Oxford University Press (OUP)
    Country: Netherlands
    Project: NWO | The Determinants of Diale... (1700115902)

    This research applies dialectometric methods to purely syntactic dialect data. It will be shown that there is geographic cohesion in syntactic variation when viewed in the aggregate. The amount of syntactic variation which can be accounted for by geography will be determined. Dialectometric techniques will be used to develop an additive measure of syntactic differences. Multidimensional scaling will be applied to visualise the geographic distribution of the Dutch dialects with respect to syntactic variation in the aggregate. The Dutch dialect map based on a syntactic measure will be compared with a dialect map based on subjective judgements and a dialect map based on pronunciation differences to put the syntactic measurement results into perspective. An alternative way to measure syntactic distance will be presented and will provide indications for future research to more accurately quantify syntactic variation.

  • Open Access English
    Authors: 
    D.L. Noorlander;
    Publisher: openjournals.nl
    Project: NWO | Novel strategies to impro... (2300147147)

    Michiel van Groesen (ed.), The Legacy of Dutch Brazil (New York: Cambridge University Press, 2014, x + 363 pp., isbn 978 11 07 06117 0).

  • Open Access English
    Authors: 
    Anass Bouisaghouane; Arthemy V. Kiselev;
    Country: Netherlands
    Project: NWO | Pre-Hamiltonian formalism... (2300137310)

    From the paper "Formality Conjecture" (Ascona 1996): "I am aware of only one such a class, it corresponds to simplest good graph, the complete graph with $4$ vertices $($and $6$ edges$)$. This class gives a remarkable vector field on the space of bi-vector fields on $\mathbb{R}^{d}$. The evolution with respect to the time $t$ is described by the following non-linear partial differential equation: ..., where $\alpha=\sum_{i,j}\alpha_{ij} {\partial}/{\partial x_{i}}\wedge {\partial}/{\partial x_{j}}$ is a bi-vector field on $\mathbb{R}^d$. It follows from general properties of cohomology that $1)$ this evolution preserves the class of $($real-analytic$)$ Poisson structures}, ... In fact, I cheated a little bit. In the formula for the vector field on the space of bivector fields which one get from the tetrahedron graph, an additional term is present. ... It is possible to prove formally that if $\alpha$ is a Poisson bracket, i.e. if $[{\alpha,\alpha}]=0\in T^2(\mathbb{R}^d)$, then the additional term shown above vanishes." By using twelve Poisson structures with high-degree polynomial coefficients as explicit counterexamples, we show that both the above claims are false: neither does the first flow preserve the property of bi-vectors to be Poisson nor does the second flow vanish identically at Poisson bi-vectors. The counterexamples at hand suggest a correction to the formula for the "exotic" flow on the space of Poisson bi-vectors; in fact, this flow is encoded by the balanced sum involving both the Kontsevich tetrahedral graphs (that give rise to the flows mentioned above). We reveal that it is only the balance $1:6$ for which the flow does preserve the space of Poisson bi-vectors. Comment: Talks given in parallel by A.B. at GADEIS VIII workshop (12--16 June 2016, Larnaca, Cyprus) and A.K. at ISQS'24 conference (13--19 June 2016, CVUT Prague, Czech Republic), 10 pages, 2 figures, 4 tables

Advanced search in Research products
Research products
arrow_drop_down
Searching FieldsTerms
Any field
arrow_drop_down
includes
arrow_drop_down
Include:
The following results are related to Digital Humanities and Cultural Heritage. Are you interested to view more results? Visit OpenAIRE - Explore.
273 Research products, page 1 of 28
  • Publication . Other literature type . Article . Preprint . 2016 . Embargo End Date: 01 Jan 2016
    Open Access English
    Authors: 
    Plonka, A.I.; Blom, N.A.; Fichtner, A.; Seismology; NWO-VIDI: Full waveform inversion for upper-mantle density structure;
    Publisher: ETH Zurich
    Countries: Switzerland, Netherlands
    Project: NWO | Full waveform inversion f... (2300172344)

    Density heterogeneities are the source of mass transport in the Earth. However, the 3-D density structure remains poorly constrained because travel times of seismic waves are only weakly sensitive to density. Inspired by recent developments in seismic waveform tomography, we investigate whether the visibility of 3-D density heterogeneities may be improved by inverting not only travel times of specific seismic phases but complete seismograms. As a first step in this direction, we perform numerical experiments to estimate the effect of 3-D crustal density heterogeneities on regional seismic wave propagation. While a finite number of numerical experiments may not capture the full range of possible scenarios, our results still indicate that realistic crustal density variations may lead to travel-time shifts of up to ∼ 1s and amplitude variations of several tens of percent over propagation distances of ∼ 1000km. Both amplitude and travel-time variations increase with increasing epicentral distance and increasing medium complexity, i.e. decreasing correlation length of the heterogeneities. They are practically negligible when the correlation length of the heterogeneities is much larger than the wavelength. However, when the correlation length approaches the wavelength, density-induced waveform perturbations become prominent. Recent regional-scale full-waveform inversions that resolve structure at the scale of a wavelength already reach this regime. Our numerical experiments suggest that waveform perturbations induced by realistic crustal density variations can be observed in high-quality regional seismic data. While density-induced travel-time differences will often be small, amplitude variations exceeding ±10% are comparable to those induced by 3-D velocity structure and attenuation. While these results certainly encourage more research on the development of 3-D density tomography, they also suggest that current full-waveform inversions that use amplitude information may be biased due to the neglect of 3-D variations in density. Solid Earth, 7 (6) ISSN:1869-9510 ISSN:1869-9529

  • Open Access English
    Authors: 
    Nataliya M. Komarova; Olav Velthuis;
    Country: Netherlands
    Project: NWO | The Globalization of High... (2300162562)

    ABSTRACTThe paper studies how local contexts contribute to the emergence of markets. In particular, it explains how potential entrepreneurs are motivated to become active in establishing new markets. Empirically, the focus is on contemporary art markets in two emerging countries: India and Russia. The paper draws upon qualitative interviews with 65 contemporary art dealers conducted in New Delhi, Mumbai, Moscow and Saint Petersburg. We show how different socio-cultural contexts function as activation mechanisms: in India, family backgrounds predominantly structure the decision-making processes, among others through the economic, social and cultural capital which these families provide. In Russia, by contrast, such family background is non-existent. Instead, the socio-economic turmoil of 1990s and 2000s as well as the strong involvement of the state function as activation mechanisms. We suggest that these different activation mechanisms contribute to explaining the diverging market performance in both coun...

  • Open Access English
    Authors: 
    Beddow, Helen M.; Liebrand, Diederik; Wilson, Douglas S.; Hilgen, Frits J.; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.; Stratigraphy and paleontology; Marine palynology and palaeoceanography; Stratigraphy & paleontology;
    Country: Netherlands
    Project: EC | ERAS (293741), EC | EARTHSEQUENCING (617462), NWO | Evolution of astronomical... (2300157723)

    Astronomical tuning of sediment sequences requires both unambiguous cycle pattern recognition in climate proxy records and astronomical solutions, as well as independent information about the phase relationship between these two. Here we present two different astronomically tuned age models for the Oligocene–Miocene transition (OMT) from Integrated Ocean Drilling Program Site U1334 (equatorial Pacific Ocean) to assess the effect tuning has on astronomically calibrated ages and the geologic timescale. These alternative age models (roughly from ∼ 22 to ∼ 24 Ma) are based on different tunings between proxy records and eccentricity: the first age model is based on an aligning CaCO3 weight (wt%) to Earth's orbital eccentricity, and the second age model is based on a direct age calibration of benthic foraminiferal stable carbon isotope ratios (δ13C) to eccentricity. To independently test which tuned age model and associated tuning assumptions are in best agreement with independent ages based on tectonic plate-pair spreading rates, we assign the tuned ages to magnetostratigraphic reversals identified in deep-marine magnetic anomaly profiles. Subsequently, we compute tectonic plate-pair spreading rates based on the tuned ages. The resultant alternative spreading-rate histories indicate that the CaCO3 tuned age model is most consistent with a conservative assumption of constant, or linearly changing, spreading rates. The CaCO3 tuned age model thus provides robust ages and durations for polarity chrons C6Bn.1n–C7n.1r, which are not based on astronomical tuning in the latest iteration of the geologic timescale. Furthermore, it provides independent evidence that the relatively large (several 10 000 years) time lags documented in the benthic foraminiferal isotope records relative to orbital eccentricity constitute a real feature of the Oligocene–Miocene climate system and carbon cycle. The age constraints from Site U1334 thus indicate that the delayed responses of the Oligocene–Miocene climate–cryosphere system and (marine) carbon cycle resulted from highly non-linear feedbacks to astronomical forcing.

  • Publication . Article . 2009
    Open Access English
    Authors: 
    Galit W. Sassoon;
    Country: Netherlands
    Project: NWO | Modeling the role of vagu... (2300152423)

    This paper presents a novel semantic analysis of unit names (like pound and meter) and gradable adjectives (like tall, short and happy), inspired by measurement theory (Krantz et al. In Foundations of measurement: Additive and Polynomial Representations, 1971). Based on measurement theory’s four-way typology of measures, I claim that different adjectives are associated with different types of measures whose special characteristics, together with features of the relations denoted by unit names, explain the puzzling limited distribution of measure phrases, as well as unit-based comparisons between predicates (as in the table is longer than it is wide). All considered, my analyses support the view that the grammar of natural languages is sensitive to features of measurement theory.

  • Open Access
    Authors: 
    P. Marcos Crichigno; Takuya Matsumoto; Kentaroh Yoshida;
    Publisher: IOP Publishing
    Project: NWO | Geometrical aspects of su... (2300157346)

    Yang-Baxter sigma models, proposed by Klimcik and Delduc-Magro-Vicedo, have been recognized as a powerful framework for studying integrable deformations of two-dimensional non-linear sigma models. In this short article, as an important generalization, we review a non-integrable sigma model in the Yang-Baxter sigma model approach based on [arXiv:1406.2249]. In particular, we discuss a family of deformations of the 5D Sasaki-Einstein manifold $T^{1,1}$, instead of the standard deformations of the $5$-sphere S$^5$. For this purpose, we first describe a novel construction of $T^{1,1}$ as a supercoset, and provide a physical interpretation of this construction from viewpoint of the dual Klebanov-Witten field theory. Secondly, we consider a $3$-parameter deformation of $T^{1,1}$ by using classical $r$-matrices satisfying the classical Yang--Baxter equation (CYBE). The resulting metric and NS-NS two-form completely agree with the ones previously obtained via TsT (T-dual -- shift -- T-dual) transformations, and contain the Lunin-Maldacena background as a special case. Our result indicates that what we refer to as the gravity/CYBE(Classical Yang-Baxter Equation) correspondence can be extended beyond integrable cosets. Comment: This article is a brief review of the original paper [arXiv:1406.2249] prepared for a proceeding of a talk given by T.M. at "The XXIIIth International Conference on Integrable Systems and Quantum symmetries (ISQS-23)" held in Prague, Czech Republic, from June 23 till June 27, 2015, v2: references added

  • Publication . Preprint . Conference object . Article . 2017
    Open Access English
    Authors: 
    Fadaee, M.; Bisazza, A.; Monz, C.; Barzilay, R.; Kan, M.-Y.;
    Publisher: Association for Computational Linguistics
    Country: Netherlands
    Project: NWO | Surface Realization in St... (2300172930)

    The quality of a Neural Machine Translation system depends substantially on the availability of sizable parallel corpora. For low-resource language pairs this is not the case, resulting in poor translation quality. Inspired by work in computer vision, we propose a novel data augmentation approach that targets low-frequency words by generating new sentence pairs containing rare words in new, synthetically created contexts. Experimental results on simulated low-resource settings show that our method improves translation quality by up to 2.9 BLEU points over the baseline and up to 3.2 BLEU over back-translation. Comment: 5 pages, 2 figures, Accepted at ACL 2017

  • Open Access
    Authors: 
    Eric Bouwers; Martin Bravenboer; Eelco Visser;
    Publisher: Elsevier BV
    Project: NWO | TraCE: Capturing Timeline... (1800113975)

    AbstractA wide range of parser generators are used to generate parsers for programming languages. The grammar formalisms that come with parser generators provide different approaches for defining operator precedence. Some generators (e.g. YACC) support precedence declarations, others require the grammar to be unambiguous, thus encoding the precedence rules. Even if the grammar formalism provides precedence rules, a particular grammar might not use it. The result is grammar variants implementing the same language. For the C language, the GNU Compiler uses YACC with precedence rules, the C-Transformers uses SDF without priorities, while the SDF library does use priorities. For PHP, Zend uses YACC with precedence rules, whereas PHP-front uses SDF with priority and associativity declarations.The variance between grammars raises the question if the precedence rules of one grammar are compatible with those of another. This is usually not obvious, since some languages have complex precedence rules. Also, for some parser generators the semantics of precedence rules is defined operationally, which makes it hard to reason about their effect on the defined language. We present a method and tool for comparing the precedence rules of different grammars and parser generators. Although it is undecidable whether two grammars define the same language, this tool provides support for comparing and recovering precedence rules, which is especially useful for reliable migration of a grammar from one grammar formalism to another. We evaluate our method by the application to non-trivial mainstream programming languages, such as PHP and C.

  • Open Access
    Authors: 
    Marco Spruit;
    Publisher: Oxford University Press (OUP)
    Country: Netherlands
    Project: NWO | The Determinants of Diale... (1700115902)

    This research applies dialectometric methods to purely syntactic dialect data. It will be shown that there is geographic cohesion in syntactic variation when viewed in the aggregate. The amount of syntactic variation which can be accounted for by geography will be determined. Dialectometric techniques will be used to develop an additive measure of syntactic differences. Multidimensional scaling will be applied to visualise the geographic distribution of the Dutch dialects with respect to syntactic variation in the aggregate. The Dutch dialect map based on a syntactic measure will be compared with a dialect map based on subjective judgements and a dialect map based on pronunciation differences to put the syntactic measurement results into perspective. An alternative way to measure syntactic distance will be presented and will provide indications for future research to more accurately quantify syntactic variation.

  • Open Access English
    Authors: 
    D.L. Noorlander;
    Publisher: openjournals.nl
    Project: NWO | Novel strategies to impro... (2300147147)

    Michiel van Groesen (ed.), The Legacy of Dutch Brazil (New York: Cambridge University Press, 2014, x + 363 pp., isbn 978 11 07 06117 0).

  • Open Access English
    Authors: 
    Anass Bouisaghouane; Arthemy V. Kiselev;
    Country: Netherlands
    Project: NWO | Pre-Hamiltonian formalism... (2300137310)

    From the paper "Formality Conjecture" (Ascona 1996): "I am aware of only one such a class, it corresponds to simplest good graph, the complete graph with $4$ vertices $($and $6$ edges$)$. This class gives a remarkable vector field on the space of bi-vector fields on $\mathbb{R}^{d}$. The evolution with respect to the time $t$ is described by the following non-linear partial differential equation: ..., where $\alpha=\sum_{i,j}\alpha_{ij} {\partial}/{\partial x_{i}}\wedge {\partial}/{\partial x_{j}}$ is a bi-vector field on $\mathbb{R}^d$. It follows from general properties of cohomology that $1)$ this evolution preserves the class of $($real-analytic$)$ Poisson structures}, ... In fact, I cheated a little bit. In the formula for the vector field on the space of bivector fields which one get from the tetrahedron graph, an additional term is present. ... It is possible to prove formally that if $\alpha$ is a Poisson bracket, i.e. if $[{\alpha,\alpha}]=0\in T^2(\mathbb{R}^d)$, then the additional term shown above vanishes." By using twelve Poisson structures with high-degree polynomial coefficients as explicit counterexamples, we show that both the above claims are false: neither does the first flow preserve the property of bi-vectors to be Poisson nor does the second flow vanish identically at Poisson bi-vectors. The counterexamples at hand suggest a correction to the formula for the "exotic" flow on the space of Poisson bi-vectors; in fact, this flow is encoded by the balanced sum involving both the Kontsevich tetrahedral graphs (that give rise to the flows mentioned above). We reveal that it is only the balance $1:6$ for which the flow does preserve the space of Poisson bi-vectors. Comment: Talks given in parallel by A.B. at GADEIS VIII workshop (12--16 June 2016, Larnaca, Cyprus) and A.K. at ISQS'24 conference (13--19 June 2016, CVUT Prague, Czech Republic), 10 pages, 2 figures, 4 tables