Deep Policies for Width-Based Planning in Pixel Domains

Width-based planning has demonstrated great success in recent years due to its ability to scale independently of the size of the state space. For example, Bandres et al. (2018) introduced a rollout version of the Iterated Width algorithm whose performance compares well with humans and learning methods in the pixel setting of the Atari games suite. In this setting, planning is done on-line using the "screen" states and selecting actions by looking ahead into the future. However, this algorithm is purely exploratory and does not leverage past reward information. Furthermore, it requires the state to be factored into features that need to be pre-defined for the particular task, e.g., the B-PROST pixel features. In this work, we extend width-based planning by incorporating an explicit policy in the action selection mechanism. Our method, called $\pi$-IW, interleaves width-based planning and policy learning using the state-actions visited by the planner. The policy estimate takes the form of a neural network and is in turn used to guide the planning step, thus reinforcing promising paths. Surprisingly, we observe that the representation learned by the neural network can be used as a feature space for the width-based planner without degrading its performance, thus removing the requirement of pre-defined features for the planner. We compare $\pi$-IW with previous width-based methods and with AlphaZero, a method that also interleaves planning and learning, in simple environments, and show that $\pi$-IW has superior performance. We also show that $\pi$-IW algorithm outperforms previous width-based methods in the pixel setting of Atari games suite.Comment: In Proceedings of the 29th International Conference on Automated Planning and Scheduling (ICAPS 2019). arXiv admin note: text overlap with arXiv:1806.0589

Learning Classical Planning Strategies with Policy Gradient

A common paradigm in classical planning is heuristic forward search. Forward search planners often rely on simple best-first search which remains fixed throughout the search process. In this paper, we introduce a novel search framework capable of alternating between several forward search approaches while solving a particular planning problem. Selection of the approach is performed using a trainable stochastic policy, mapping the state of the search to a probability distribution over the approaches. This enables using policy gradient to learn search strategies tailored to a specific distributions of planning problems and a selected performance metric, e.g. the IPC score. We instantiate the framework by constructing a policy space consisting of five search approaches and a two-dimensional representation of the planner's state. Then, we train the system on randomly generated problems from five IPC domains using three different performance metrics. Our experimental results show that the learner is able to discover domain-specific search strategies, improving the planner's performance relative to the baselines of plain best-first search and a uniform policy.Comment: Accepted for ICAPS 201

Road Expansion and Urban Highways: Consequences Outweigh Benefits in Kathmandu

Rapid urbanization has transformed Kathmandu Valley, Nepal, one of the fastest growing metropolitan regions in South Asia. This urbanization, in turn, is leading to considerable social, economic, and environmental stress. The region has seen unplanned growth despite continued planning exercises. In 2011, in response to the rapid urbanization then Prime Minster Baburam Bhattarai initiated road expansion throughout the city to reduce traffic congestion. By mid 2015, it was clear that the road expansion induced greater demand leading to further traffic congestion rather than alleviating the problem. Today, non-motorized (pedestrians and bicycle) road users are more unsafe on the roads than ever before, and the plight of public transport users has remained the same. Traffic congestion has become a more serious problem. Air pollution associated with road construction and an increasing number of vehicles has turned the Kathmandu Valley into a dust bowl with potential for serious human health consequences. Along with road expansion, the government’s inability to regulate land use has contributed to Kathmandu’s current urban sprawl. Road expansion done without proper planning has threatened traditional settlements, many with heritage sites, and led to loss of public spaces and temple courtyards to make space for increasing demand for parking. Another major landscape change has been the building of concrete embankments and exclusive motor roads along the river corridors. The road expansion campaign is still ongoing and is a top priority of the government’s efforts to reduce congestion and improve urban transportation. It is high time the government of Nepal rethinks its vehicle-centric urban transport policy and adopts policy where mobility of people is prioritized. Urban transport planning should work to build a more equitable and inclusive city while addressing accessibility, safety, and environmental health risks of its growing urban population. Today, non-motorized users (pedestrians and bicycle users) are unsafe on the roads than ever before, and the plight of public transport users has remained the same. Road expansion has led to destruction of traditional settlements many with heritage sites and loss of public spaces and temple courtyards to make space for increasing parking demand. Another major landscape change has been the building of concrete embankments and exclusive motor roads along the river corridors. Air pollution associated with road construction and increasing number of vehicles has turned the valley into a dust bowl with potential for serious human health consequences. Along with the road expansion, the government’s inability to regulate proper landuse has contributed to Kathmandu’s current urban sprawl. The road expansion drive is still ongoing and is still the priority for government’s urban transportation initiatives within the Valley. It is high time the government of Nepal rethinks its vehicle-centric urban transport policy and adopts policy where mobility of people is prioritized. Urban transport planning should work on building more equitable and inclusive city while addressing accessibility, safety, and environmental health risk associated for its growing urban population

The built environment, Hamilton City Council policies and child driveway safety: a balancing act

Driveway run-overs continue to bring tragedy to New Zealand families at a higher rate than any other Western nation. Meanwhile, little progress appears to have been made in regard to the recommendations of previous research. This project investigates whether recommendations in regard to one key factor in driveway run-overs, the built environment, are reflected in current local body policies and regulations. The research evaluates Hamilton City Council policies affecting the renovation and/or erection of domestic residences with a view to determining whether they are consistent with existing knowledge and best practice initiatives designed to minimise accidental injuries to children on driveways. The project compares the findings of a review of the existing literature on child safety best practice for the built environment and urban design of driveways, with a review of Hamilton City Council policies and guidelines relating to the built environment of residential properties and adjacent roads (the Operative District Plan, Ten Year Plan, Urban Growth Strategy, Vista, and more), along with relevant central government policy. These findings are triangulated with data from interviews with four expert informants – one child safety expert and three Hamilton City Council employees involved in planning, policy and transport – who provide insights into the translation of policies into practice

Urban land planning: The role of a Master Plan in influencing local temperatures

Land use planning (LUP) is central for managing issues related to climatic variation in urban environments. However, Master Plans (MPs) usually do not include climatic aspects, and few studies have addressed climate change at the urban scale, especially in developing countries. This paper proposes a framework with ten categories for assessment of climatic variation in urban LUP. Each category comprises attributes that describe a complex of relationships in influencing local temperature variations. They are analyzed for the case of the Master Plan of Porto Alegre (MPPA), the Southernmost metropolis of Brazil. It is concluded that the MPPA is strongly grounded in climate-related land and zoning coordination, but exhibits weaknesses in building, cartographical and social aspects considered synergistically relevant for tackling problems related to urban climate variation. Furthermore, the MPPA does not contain provisions related to monitoring of local climate and greenhouse gases (GHG) emissions and it is ineffective for improving energy efficiency. Specific MPPA failures stemming from these weaknesses include: an increase of 21.79% in the city's urbanized area from 1986 to 2011 to accommodate a similar increase in population, with significant horizontal sprawl; average temperature rise of 0.392. °C from 1991-2000 to 2001-2010, with statistically significant increases in temperature found since 1931; significant vehicle traffic increases, especially since 2007. From these findings, it is possible to conclude that the MPPA does not offer answers to all the imbalances related to land use, and therefore gives insufficient support to tackle the issue of rising temperatures

Divide and Sprawl, Decline and Fall: A Comparative Critique of Euclidean Zoning

As many commentators have pointed out, the land use patterns prevalent in the United States since the advent of Euclidean-style zoning have played a direct role in the development of a surprisingly broad range of problems: “[b]y fostering or requiring low density development with a high separation of uses, Euclidean zoning is one of the great generators of suburban sprawl, with all of its environmental, economic, and social costs.” These costs include pollution, loss of wilderness and farmland, racial and socioeconomic segregation of the population, and legal obstacles to effective urban rehabilitation.6 Moreover, in combination with prevailing patterns of local funding, the socioeconomic segregation caused by Euclidean zoning perpetuates itself by channeling less well-off children into chronically underequipped public schools and stretching the resources of many urban municipalities too thin, leaving them to choose between raising property tax rates or allowing their infrastructure to decay. That devil’s bargain bolsters the tendency of middle- and higher-income people to live in suburbs rather than cities, deepening the downward spiral in which many American cities find themselves. And the damage goes even further: “many current zoning practices disregard or even work against crime prevention goals” in both cities and suburbs. This is particularly problematic in light of the fact that “Euclidean systems of separation—conventional zoning—have been implemented ubiquitously” in the United States: “[a]bout ninety-seven percent of incorporated communities zone.