New Zealand

Igor Goncharenko, Mikhail Svinin, Shigeyuki Hosoe and Sven Forstmann (April 1st 2010). On the Influence of Hand Dynamics on Motion Planning of Reaching Movements in Haptic Environments, Advances in Haptics, Mehrdad Hosseini Zadeh, IntechOpen, DOI: 10.5772/8693.

Michael Strolz and Martin Buss (April 1st 2010). Real-Time Support of Haptic Interaction by Means of Sampling-Based Path Planning, Advances in Haptics, Mehrdad Hosseini Zadeh, IntechOpen, DOI: 10.5772/8689. 

This talk describes a policy search approach for railway scheduling using the covariance matrix adaptation evolution strategy (CMA-ES). The goal is to define arrival/departure times and track allocations for all trains such that the resource and operating constraints of the railway line are satisfied, and priority-weighted train departure delay is minimised. The proposed approach is scalable in the sense that (i) the optimised policy can be applied to an arbitrarily long railway line, independent of the number of trains, tracks, and stations, and (ii) the on-line implementation is computationally light enough to be applied in real-time. Our experiments show that policies computed with CMA-ES are able to produce solutions with lower priorityweighted delay than heuristics and reinforcement learning (RL) algorithms reported in literature, on synthetic examples as well as actual railway line data from portions of the Indian Railway network.

AAMAS 2020

Optimising a Real-Time Scheduler for Railway Lines using Policy Search

railway scheduling

evolutionary policy search

planning

### Welcome to Navigation 2021!

Our aim was to bring diverse disciplines together to stimulate insights and knowledge sharing towards a more navigable world. We hope we achieved this!

Navigation and timing are critical to the world we all inhabit. We believe that the work of the wider navigation community enables societal benefit including support to national grand challenges and also the United Nations’ Sustainable Development Goals. To achieve this requires collaboration and understanding across science, technology and practice.

Navigation 2021 is about much more than technology innovation, it also showcases science and research from across the wider community, including animal navigation, cognition and human factors.


Navigation 2021

Our aim was to bring diverse disciplines together to stimulate insights and knowledge sharing towards a more navigable world. We hope we achieved this!

technical paper

AAMAS is the leading scientific conference for research in autonomous agents and multi-agent systems. The AAMAS conference series was initiated in 2002 as the merging of three respected scientific meetings: the International Conference on Multi-Agent Systems (ICMAS), the International Workshop on Agent Theories, Architectures, and Languages (ATAL), and the International Conference on Autonomous Agents (AA). The aim of the joint conference is to provide a single, high-profile, internationally-respected archival forum for scientific research in the theory and practice of autonomous agents and multi-agent systems.

Browse keynotes, discussions, panels and over 300 presentations.


AAMAS is the leading scientific conference for research in autonomous agents and multi-agent systems. The AAMAS conference series was initiated in 2002 as the merging of three respected scientific meetings: the International Conference on Multi-Agent Systems (ICMAS), the International Workshop on Agent Theories, Architectures, and Languages (ATAL), and the International Conference on Autonomous Agents (AA). 

Robustness is an important property of software systems, and the availability of proper feedback is seen as crucial to obtain it, especially in the case of systems of distributed and interconnected components.
Multiagent Systems (MAS) are valuable for conceptualizing and implementing distributed systems, but the current design methodologies for MAS fall short in addressing robustness in a systematic way at design time.
In this paper we outline our vision of how robustness in MAS can be granted as a design property. To this end, we exploit the notion of accountability as a mechanism for building reporting frameworks and, then, we describe how robustness is gained.
We exemplify our vision on the JaCaMo agent platform.

Fragility and Robustness in Multiagent Systems

Reinforcement learning requires exploration, leading to repeated execution of sub-optimal actions. Naive exploration techniques address this problem by changing gradually from exploration to exploitation. This approach employs a wide search resulting in exhaustive exploration and low sample-efficiency. More advanced search methods explore optimistically based on an upper bound estimate of expected rewards. These methods employ deep search, aiming to reach states not previously visited. Another deep search strategy is found in action-elimination methods, which aim to discover and eliminate sub-optimal actions. Despite the effectiveness of advanced deep search strategies, some problems are better suited to naive exploration. We devise a new method, called Interval Q-Learning, that finds a balance between wide and deep search. It assigns a small probability to taking sub-optimal actions and combines both greedy and optimistic exploration. This allows for fast convergence to a near-optimal policy, and then exploration around it. We demonstrate the performance of tabular and deep Q-network versions of Interval Q-Learning, showing that it offers convergence speed-up both in problems that favor wide exploration methods and those that favor deep search strategies.


Interval Q-Learning: Balancing Deep and Wide Exploration

Epidemics of infectious diseases are an important threat to public health and global economies. 
Yet, the development of prevention strategies remains a challenging process.
For this reason, we investigate a deep reinforcement learning approach to automatically learn prevention strategies in an epidemiological model, in the context of pandemic influenza.
To this end, we construct a new epidemiological meta-population model, with 379 patches, that balances between model complexity and computational efficiency such that the use of reinforcement learning techniques becomes attainable.
First, we set up a ground truth such that we can evaluate the performance of the ""Proximal Policy Optimization"" algorithm to learn in a single district of this epidemiological model.
Next, we consider a larger scale problem, by conducting an experiment where we aim to learn a joint policy to control the districts in a community of 11 tightly coupled districts, for which no ground truth can be established. 
This experiment shows that deep reinforcement learning can be used to learn mitigation policies in complex epidemiological models with a large state space.
Moreover, through this experiment, we demonstrate that there can be an advantage to consider collaboration between districts when designing prevention strategies.


Deep reinforcement learning for large-scale epidemic control

Reward Redistribution Mechanism in Multi-Agent Reinforcement Learning

Option discovery and skill acquisition frameworks are integral to the functioning of a hierarchically organized Reinforcement learning agent. However, such techniques often yield a large number of options or skills, which can be represented succinctly by filtering out any redundant information. Such a reduction can decrease the required computation while also improving the performance on a target task. To compress an array of option policies, we attempt to find a policy basis that accurately captures the set of all options. In this work, we propose Option Encoder, an auto-encoder based framework with intelligently constrained weights, that helps discover a collection of basis policies. The policy basis can be used as a proxy for the original set of skills in a suitable hierarchically organized framework. We demonstrate the efficacy of our method on a collection of grid-worlds and Deepmind-lab by evaluating the obtained policy basis on downstream tasks.


Option Encoder : A framework for Discovering a Policy Basis in Reinforcement Learning

Electric power sharing among households based on the bidding method is studied as a future service. In order to verify the feasibility of such a service, a new multi-agent simulation model has been designed. We validated this model through some evaluations. For example, it is confirmed that the market price on this service stably changes according to the supply-demand balance between both sold and purchased bid volumes. In addition to that, the results of the household profit and contract rate of this service showed that the design for bid strategies works as intended in most cases.


Design and Evaluations of Multi-Agent Simulation Model for Electric Power Sharing among Households

We present a reinforcement learning-based approach for generating a timetable for trains traversing through a railway station.
We demonstrate how the reinforcement learning approach is used to learn heuristics, which in turn are used to generate a train movement plan.
We compare the quality of the plan generated using ‘rules used in practice’ and the plan generated by the ‘heuristics learned using the RL approach’, under different congestion scenarios
"


Reinforcement Learning for Train Movement Planning at Railway Stations

We study proportionality in approval-based multi- winner elections with a variable number of winners, where both the size and identity of the winning committee are informed by voters’ opinions. While proportionality has been studied in multi- winner elections with a fixed number of winners, it has not been considered in the variable number of winners setting. The measure of proportionality we consider is average satisfaction (AS), which intuitively measures the number of agreements on aver- age between sufficiently large and cohesive groups of voters and the output of the voting rule. First, we show an upper bound on the AS that any deterministic rule can provide, and that straightforward adaptations of deterministic rules from the fixed number of winners setting do not achieve better than a 1/2 approximation to AS even for large numbers of candidates. We then prove that a natural randomized rule achieves a 29/32 approximation to AS.


Proportionality in Approval-Based Elections With a Variable Number of Winners

Condorcet extensions have long held a prominent place in social choice theory. A Condorcet extension will return the Condorcet winner as the unique winner whenever such an alternative exists. However, the definition of a Condorcet extension does not take into account possible manipulation by the voters. A profile where all agents vote truthfully may have a Condorcet winner, but this alternative may not end up in the set of winners if agents are acting strategically. Focusing on the class of tournament solutions, we show that many natural social choice functions in this class, such as the well-known Copeland and Slater rules, cannot guarantee the preservation of Condorcet winners when agents behave strategically. Our main result in this respect is an impossibility theorem that establishes that no tournament solution satisfying a very weak decisiveness requirement can provide such a guarantee. On the bright side, we identify several indecisive but otherwise attractive tournament solutions that do guarantee the preservation of Condorcet winners under strategic manipulation.


Preserving Condorcet Winners under Strategic Manipulation

We present MsATL: the first tool for deciding the satisfiability of Alternating-time Temporal Logic (ATL) with imperfect information. MsATL combines SAT Modulo Monotonic Theories solvers with existing ATL model checkers: MCMAS and STV. The tool can deal with various semantics of ATL, including perfect and imperfect information, and can handle additional practical requirements. MsATL can be applied for synthesis of games that conform to a given specification, with the synthesised game often being minimal.


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Fragility and Robustness in Multiagent Systems

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Fragility and Robustness in Multiagent Systems

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