Happy-GLL: modular, reusable and complete top-down parsers for parameterized nonterminals

Parser generators and parser combinator libraries are the most popular tools for producing parsers. Parser combinators use the host language to provide reusable components in the form of higher-order functions with parsers as parameters. Very few parser generators support this kind of reuse through abstraction and even fewer generate parsers that are as modular and reusable as the parts of the grammar for which they are produced. This paper presents a strategy for generating modular, reusable and complete top-down parsers from syntax descriptions with parameterized nonterminals, based on the FUN-GLL variant of the GLL algorithm. The strategy is discussed and demonstrated as a novel back-end for the Happy parser generator. Happy grammars can contain `parameterized nonterminals' in which parameters abstract over grammar symbols, granting an abstraction mechanism to define reusable grammar operators. However, the existing Happy back-ends do not deliver on the full potential of parameterized nonterminals as parameterized nonterminals cannot be reused across grammars. Moreover, the parser generation process may fail to terminate or may result in exponentially large parsers generated in an exponential amount of time. The GLL back-end presented in this paper implements parameterized nonterminals successfully by generating higher-order functions that resemble parser combinators, inheriting all the advantages of top-down parsing. The back-end is capable of generating parsers for the full class of context-free grammars, generates parsers in linear time and generates parsers that find all derivations of the input string. To our knowledge, the presented GLL back-end makes Happy the first parser generator that combines all these features. This paper describes the translation procedure of the GLL back-end and compares it to the LALR and GLR back-ends of Happy in several experiments.Comment: 15 page

Tidal influence on Rutford Ice Stream, West Antarctica: observations of surface flow and basal processes from closely-spaced GPS and passive seismic stations

High-resolution surface velocity measurements and passive seismic observations from Rutford Ice Stream, West Antarctica, 40 km upstream from the grounding line are presented. These measurements indicate a complex relationship between the ocean tides and currents, basal conditions and ice-stream flow. Both the mean basal seismicity and the velocity of the ice stream are modulated by the tides. Seismic activity increases twice during each semi-diurnal tidal cycle. The tidal analysis shows the largest velocity variation is at the fortnightly period, with smaller variations superimposed at diurnal and semi-diurnal frequencies. The general pattern of the observed velocity is two velocity peaks during each semi-diurnal tidal cycle, but sometimes three peaks are observed. This pattern of two or three peaks is more regular during spring tides, when the largest-amplitude velocity variations are observed, than during neap tides. This is the first time that velocity and level of seismicity are shown to correlate and respond to tidal forcing as far as 40 km upstream from the grounding line of a large ice stream

RELACIÓN SER HUMANO-NATURALEZA: DEBATIENDO EL DESARROLLO SOSTENIBLE DESDE LA FILOSOFÍA DE LA CIENCIA

The global ecological-economic dynamic tends to foment a false dichotomy between human beings and nature. This logic has generated a debate over the role of interdisciplinary approaches to eco-social studies. With an eye towards enriching this debate we propose a theoretical reflection on the human-nature relation y how emergent interdisciplinary connections provide a response in a society undergoing constant change

Towards a statistical mechanics of nonabelian vortices

A study is presented of classical field configurations describing nonabelian vortices in two spatial dimensions, when a global $SO(3)$ symmetry is spontaneously broken to a discrete group \IK isomorphic to the group of integers mod 4. The vortices in this model are characterized by the nonabelian fundamental group \pi_1 (SO(3)/{\IK}) , which is isomorphic to the group of quaternions. We present an ansatz describing isolated vortices and prove that it is stable to perturbations. Kinematic constraints are derived which imply that at a finite temperature, only two species of vortices are stable to decay, due to `dissociation'. The latter process is the nonabelian analogue of the instability of charge $|q| >1$ abelian vortices to dissociation into those with charge $|q| = 1$. The energy of configurations containing at maximum two vortex-antivortex pairs, is then computed. When the pairs are all of the same type, we find the usual Coulombic interaction energy as in the abelian case. When they are different, one finds novel interactions which are a departure from Coulomb like behavior. Therefore one can compute the grand canonical partition function (GCPF) for thermal pair creation of nonabelian vortices, in the approximation where the fugacities for vortices of each type are small. It is found that the vortex fugacities depend on a real continuous parameter $a$ which characterize the degeneracy of the vacuum. Depending on the relative sizes of these fugacities, the vortex gas will be dominated by one of either of the two types mentioned above. In these regimes, we expect the standard Kosterlitz-Thouless phase transitions to occur, as in systems of abelian vortices in 2-dimensions. Between these two regimes, the gas contains pairs of both types, so nonabelian effects will be important.Comment: 40 pages in a4 LaTeX including 2 tables and 5 uuencoded Postscript figures, QMW-93/15.( The 6th figure, due to its size, is available by directly request from [email protected]. Some typos are corrected and the choice of choosing \r_c has been argued.

On the SU(2)-Higgs Phase Transition

The properties of the Confinement-Higgs phase transition in the SU(2)-Higgs model with fixed modulus are investigated. We show that the system exhibits a transient behavior up to L=24 along which the order of the phase transition cannot be discerned. To get stronger conclusions about this point, without going to prohibitive large lattice sizes, we have introduced a second (next-to-nearest neighbors) gauge-Higgs coupling, k2. On this extended parameter space we find a line of phase transitions which become increasely weaker as k2 tends to 0. The results point to a first order character for the transition with the standard action (k2 = 0).Comment: Replaced with revised version, some minor changes added. Accepted for publication in Nuc. Phys.

Discrete Model of Ideological Struggle Accounting for Migration

A discrete in time model of ideological competition is formulated taking into account population migration. The model is based on interactions between global populations of non-believers and followers of different ideologies. The complex dynamics of the attracting manifolds is investigated. Conversion from one ideology to another by means of (i) mass media influence and (ii) interpersonal relations is considered. Moreover a different birth rate is assumed for different ideologies, the rate being assumed to be positive for the reference population, made of initially non-believers. Ideological competition can happen in one or several regions in space. In the latter case, migration of non-believers and adepts is allowed; this leads to an enrichment of the ideological dynamics. Finally, the current ideological situation in the Arab countries and China is commented upon from the point of view of the presently developed mathematical model. The massive forced conversion by Ottoman Turks in the Balkans is briefly discussed.Comment: 24 pages, with 5 figures and 52 refs.; prepared for a Special issue of Advances in Complex System

Daily mood, partner support, sexual interest, and sexual activity among adolescent women

This is a post print version of the article. The official published version can be accessed from the link below.Objective: to examine day-to-day associations of coitus, sexual interest, partner emotional support, negative mood and positive mood among adolescent women. Methods: Women (ages 14 – 17 at enrollment; N=146) enrolled from one of three adolescent primary care clinics completed up to five 84-day diaries over a 27-month period. The diaries assessed partner interactions, sexual activity, substance use and mood. Partner-specific measures assessed on each day included partner emotional support (4 items; alpha = 0.94), argument with a partner (no/yes) and coitus (no/yes). Within-day measures assessed marijuana use (no/yes), Positive Mood (3-items; alpha = 0. 86); Negative Mood (3-items; alpha = 0.82) and Sexual Interest (1-item). Lagged measures of mood and sexual activity were included in multivariate models to control for recent mood and sexual behavior effects on current day mood and coitus. Two main analyses were conducted: coitus as a predictor of positive and negative mood; and the role of positive and negative mood as predictors of coitus. Analyses were conducted by multivariate mixed effect regression and mixed effect logistic regression models. Results: Data represent 28,376 days from 146 participants. The average number of diary days was 194 days per participant. Sexual activity was reported on 8.3% of days, with condoms used for 27.0% of these coital events. Marijuana was used on 11% of days. Significant predictors of positive mood on a given day included partner support, marijuana use, and coitus. Negative mood was associated with having an argument with a partner and with prior day coitus. Predictors of coitus on a given day included age (Odds ratio = 1.22), increased coital frequency in previous week (OR = 1.49), coitus on the previous day (1.21), increased same-day sexual interest (OR = 2.8) and decreased same-day negative mood (OR = 0.92). Conclusions: The data demonstrate complex associations of sexual interest, mood, partner interactions and sexual activity

Implementing integrated care: a synthesis of experiences in three European countries

Many countries are experimenting with new models to better integrate care; yet, innovative care models are often implemented as time-limited, localised projects with limited impact on service delivery more broadly. This paper seeks to understand the processes behind successful projects that achieved some form of ‘routinisation’ and informed system-wide integrated care strategies. It draws on detailed case studies of three integrated care experiments: the ‘Integrated effort for people living with chronic diseases’ project in Denmark; the Gesundes Kinzigtal network in Germany; and Zio, a care group in the Maastricht region in the Netherlands. It explores how they were developed, implemented and sustained, and how they impacted the wider system context. All three models implicitly or explicitly adopted processes shown to be conducive to the dissemination of innovations, including dedicated time and resources, support and advocacy, leadership and management, stakeholder involvement, communication and networks, adaptation to local context and feedback. Each showed robust evidence of improvements on a number of service and patient outcomes and these findings were central to their wider impacts, shaping country-wide integrated care polices. However, the wider dissemination of projects occurred in an incremental and somewhat haphazard way. To further redesign health and social care a more formal strategy, alongside resources, may thus be needed to provide funders and providers with genuine incentives to invest in new business models of care. There remains a crucial need for better understanding of specific local conditions that influence implementation and sustainability to enable translation to other contexts and settings

Status, taste and distinction in consumer culture: acknowledging the symbolic dimensions of inequality

The relationship between social position and health has been the focus of extensive public health debate. In the UK and elsewhere, most researchers have focused on physical aspects of health, using indicators such as mortality and morbidity to draw a picture of profound and widening social inequalities. This paper draws attention to the (neglected) influence of contemporary culture on wellbeing, arguing that the social meanings created within consumer culture possess symbolic force that can add to wider inequalities. The possession of greater material and cultural resources by people of higher social status enables them to label their preferred forms of consumption and lifestyle as desirable and legitimate, thus conveying messages about superior taste and social distinction. Symbolic rather than material forms of inequality are implicated here, with consequences for the psychological wellbeing of disadvantaged people. This paper argues that analyses of inequality need broadening to include such considerations. However, there are implications for efforts to address health inequalities because this analysis suggests that if some forms of social inequality are removed, elements within society would be motivated to invent new forms to replace them. Therefore, this article suggests processes whereby people can develop the self-awareness needed to resist the glossy illusions of the good life represented by modern consumer capitalism