A Topological Pattern of Urban Street Networks: Universality and Peculiarity

In this paper, we derive a topological pattern of urban street networks using a large sample (the largest so far to the best of our knowledge) of 40 U.S. cities and a few more from elsewhere of different sizes. It is found that all the topologies of urban street networks based on street-street intersection demonstrate a small world structure, and a scale-free property for both street length and connectivity degree. More specifically, for any street network, about 80% of its streets have length or degrees less than its average value, while 20% of streets have length or degrees greater than the average. Out of the 20%, there are less than 1% of streets which can form a backbone of the street network. Based on the finding, we conjecture that the 20% streets account for 80% of traffic flow, and the 1% streets constitute a cognitive map of the urban street network. We illustrate further a peculiarity about the scale-free property.Comment: 9 pages, 6 figures, and 2 table

Land use patterns and access in Mexico City

The problem of distribution of land uses in urban space in Latin American cities has been examined under different perspectives. Most authors tend to model patterns of population and land use as a consequence of social and economic processes alone, failing to address urban space as an intrinsic variable. Instead, the theory of cities as movement economies argues that land use patterns are influenced by movement flows, which are in turn strongly affected by the urban grid. As a result, land uses such as retail would seek highly accessible locations to take advantage of such flows while residential uses would avoid them. However, space syntax techniques traditionally used to point out this relationship do not seem to reveal it so easily in non-organic cities like Mexico. This paper addresses the relationship between patterns of accessibility and land use in the first ring of Mexico City as a spatial strategy. A new functional description of the city where plots are nodes connected to flows that represent the street network is adopted. This model enables us to measure accessibility at the level of plots. Following this, we focus on the occurrence of land use types in highly or low accessible locations using cumulative distribution functions. If the distribution of land uses was random, the proportion of land use types would be more or less uniform throughout the area. It is shown that the relationship between accessibility and land use is not linear and is guided by movement economy forces. It is suggested that the understanding of these relationship is key to plan for sustainable growth objectively

The riddle of togelby

© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.At the 2017 Artificial and Computational Intelligence in Games meeting at Dagstuhl, Julian Togelius asked how to make spaces where every way of filling in the details yielded a good game. This study examines the possibility of enriching search spaces so that they contain very high rates of interesting objects, specifically game elements. While we do not answer the full challenge of finding good games throughout the space, this study highlights a number of potential avenues. These include naturally rich spaces, a simple technique for modifying a representation to search only rich parts of a larger search space, and representations that are highly expressive and so exhibit highly restricted and consequently enriched search spaces. We treat the creation of plausible road systems, useful graphics, highly expressive room placement for maps, generation of cavern-like maps, and combinatorial puzzle spaces.Final Accepted Versio

The Contagion Effects of Repeated Activation in Social Networks

Demonstrations, protests, riots, and shifts in public opinion respond to the coordinating potential of communication networks. Digital technologies have turned interpersonal networks into massive, pervasive structures that constantly pulsate with information. Here, we propose a model that aims to analyze the contagion dynamics that emerge in networks when repeated activation is allowed, that is, when actors can engage recurrently in a collective effort. We analyze how the structure of communication networks impacts on the ability to coordinate actors, and we identify the conditions under which large-scale coordination is more likely to emerge.Comment: Submitted for publicatio

In search of patterns of land-use in Mexico City using logistic regression at the plot level

The study of big cities’ tendency to decentralisation is in the current agenda to understand the structure of Latin American cities. In general, centres and subcentres are related to specific functions. According to the theories of the movement economy and centrality as a process, the urban grid shapes land use distribution through movement and therefore is the main determinant of the location of ‘live centres’, a key component of centres. Activities related to ‘live centres’ include retail, catering and other movement dependent uses. However, the distribution of this kind of activity in cities like Mexico is not as spatially clear as it is in organically grown cities. In this paper we show that, nonetheless complex, there is a relationship between the location of ‘live centre’ uses and spatial configuration. We use multiple logistic regression to evaluate exactly how much influence each variable has on the outcome ‘shop’ given the presence of all the others. The results also suggest different spatial influences for different types of retail on different scales of centres