The Experts below are selected from a list of 154088937 Experts worldwide ranked by ideXlab platform

K P Rhee - One of the best experts on this subject based on the ideXlab platform.

  • Development of collision avoidance system by using expert system and search algorithm
    International shipbuilding progress, 2001
    Co-Authors: K P Rhee
    Abstract:

    In this paper, a collision avoidance system is developed using the expert system and action space search. Fuzzy theory is used to reason the degree of collision risk, and the A * search method is used to make an avoidance action plan. The action space searched by the ship is formed in the expert system using the marine traffic rules. Simulation results demonstrate that the collision avoidance system with the expert system takes more reasonable actions than the system without it.

Jacopo Pellegrini - One of the best experts on this subject based on the ideXlab platform.

  • braid group actions on coideal subalgebras of quantized enveloping algebras
    Journal of Algebra, 2011
    Co-Authors: Stefan Kolb, Jacopo Pellegrini
    Abstract:

    Abstract We construct braid group actions on coideal subalgebras of quantized enveloping algebras which appear in the theory of quantum symmetric pairs. In particular, we construct an action of the semidirect product of Z n and the classical braid group in n strands on the coideal subalgebra corresponding to the symmetric pair ( sl 2 n ( C ) , sp 2 n ( C ) ) . This proves a conjecture by Molev and Ragoucy. We expect similar actions to exist for all symmetric simple complex Lie algebras. The given actions are inspired by Lusztigʼs braid group action on quantized enveloping algebras and are defined explicitly on generators. Braid group and algebra relations are verified with the help of the package Quagroup within the computer algebra program GAP .

  • braid group actions on coideal subalgebras of quantized enveloping algebras
    arXiv: Quantum Algebra, 2011
    Co-Authors: Stefan Kolb, Jacopo Pellegrini
    Abstract:

    We construct braid group actions on coideal subalgebras of quantized enveloping algebras which appear in the theory of quantum symmetric pairs. In particular, we construct an action of the semidirect product of Z^n and the classical braid group in n strands on the coideal subalgebra corresponding to the symmetric pair (sl_{2n}(C), sp_{2n}(C)). This proves a conjecture by Molev and Ragoucy. We expect similar actions to exist for all symmetric Lie algebras. The given actions are inspired by Lusztig's braid group action on quantized enveloping algebras and are defined explicitly on generators. Braid group and algebra relations are verified with the help of the package Quagroup within the computer algebra program GAP.

Marcel Van Der Linden - One of the best experts on this subject based on the ideXlab platform.

  • “Unanticipated Consequences of ‘Humanitarian Intervention’: The British Campaign to Abolish the Slave Trade, 1807-1900"
    Contention and Trust in Cities and States, 2011
    Co-Authors: Marcel Van Der Linden
    Abstract:

    Building on Robert Merton’s theory of unanticipated consequences of purposive action and Charles Tilly’s theory of error correction, the present article presents a stylized narrative about the British campaign to abolish the trading in African slaves, from its beginning in 1807 until the end of the nineteenth century. In the end, this campaign was largely successful, though it required error corrections that had extremely far-reaching consequences. The colonization of Africa was, to a certain extent, a second-degree unanticipated consequence. This case study suggests that three sorts of error correction can be distinguished, namely (a) measures that are taken to facilitate the effective implementation of the purposive action; (b) measures that are taken to minimize unintended consequences, after the purposive action has been carried out; and (c) new purposive actions that widen the objective and are more far-reaching than the original purposive action.

  • Unanticipated consequences of “humanitarian intervention”: The British campaign to abolish the slave trade, 1807–1900
    Theory and Society, 2010
    Co-Authors: Marcel Van Der Linden
    Abstract:

    Building on Robert Merton’s theory of unanticipated consequences of purposive action and Charles Tilly’s theory of error correction, the present article presents a stylized narrative about the British campaign to abolish the trading in African slaves, from its beginning in 1807 until the end of the nineteenth century. In the end, this campaign was largely successful, though it required error corrections that had extremely far-reaching consequences. The colonization of Africa was, to a certain extent, a second-degree unanticipated consequence. This case study suggests that three sorts of error correction can be distinguished, namely (a) measures that are taken to facilitate the effective implementation of the purposive action; (b) measures that are taken to minimize unintended consequences, after the purposive action has been carried out; and (c) new purposive actions that widen the objective and are more far-reaching than the original purposive action

Stavros Vassos - One of the best experts on this subject based on the ideXlab platform.

  • ltl verification of online executions with sensing in bounded situation calculus
    European Conference on Artificial Intelligence, 2014
    Co-Authors: Giuseppe De Giacomo, Yves Lesperance, Fabio Patrizi, Stavros Vassos
    Abstract:

    We look at agents reasoning about actions from a first-person perspective. The agent has a representation of world as situation calculus action theory. It can perform sensing actions to acquire information. The agent acts "online", i.e., it performs an action only if it is certain that the action can be executed, and collects sensing results from the actual world. When the agent reasons about its future actions, it indeed considers that it is acting online; however only possible sensing values are available. The kind of reasoning about actions we consider for the agent is verifying a first-order (FO) variant (without quantification across situations) of linear time temporal logic (LTL). We mainly focus on bounded action theories, where the number of facts that are true in any situation is bounded. The main results of this paper are: (i) possible sensing values can be based on consistency if the initial situation description is FO; (ii) for bounded action theories, progression over histories that include sensing results is always FO; (iii) for bounded theories, verifying our FO LTL against online executions with sensing is decidable.

  • transforming situation calculus action theories for optimised reasoning
    Principles of Knowledge Representation and Reasoning, 2014
    Co-Authors: Christopher James Ewin, Adrian R Pearce, Stavros Vassos
    Abstract:

    Among the most frequent reasoning tasks in the situation calculus are projection queries that query the truth of conditions in a future state of affairs. However, in long running action sequences solving the projection problem is complex. The main contribution of this work is a new technique which allows the length of the action sequences to be reduced by reordering independent actions and removing dominated actions; maintaining semantic equivalence with respect to the original action theory. This transformation allows for the removal of actions that are problematic with respect to progression, allowing for periodical update of the action theory to reflect the current state of affairs. We provide the logical framework for the general case and give specific methods for two important classes of action theories. The work provides the basis for handling more expressive cases, such as the reordering of sensing actions in order to delay progression, and forms an important step towards facilitating ongoing planning and reasoning by long-running agents. It provides a mechanism for minimising the need for keeping the action history while appealing to both regression and progression.

Christopher L Buckley - One of the best experts on this subject based on the ideXlab platform.

  • an active inference implementation of phototaxis
    European Conference on Artificial Life, 2017
    Co-Authors: Manuel Baltieri, Christopher L Buckley
    Abstract:

    Active inference is emerging as a possible unifying theory ofperception and action in cognitive and computational neuro-science. On this theory, perception is a process of inferringthe causes of sensory data by minimising the error betweenactual sensations and those predicted by an innergenerative(probabilistic) model. Action on the other hand is drawn as aprocess that modifies the world such that the consequent sen-sory input meets expectations encoded in the same internalmodel. These two processes, inferring properties of the worldand inferring actions needed to meet expectations, close thesensory/motor loop and suggest a deep symmetry betweenaction and perception. In this work we present a simpleagent-based model inspired by this new theory that offers in-sights on some of its central ideas. Previous implementationsof active inference have typically examined a “perception-oriented” view of this theory, assuming that agents are en-dowed with a detailed generative model of their surround-ing environment. In contrast, we present an “action-oriented”solution showing how adaptive behaviour can emerge evenwhen agents operate with a simple model which bears littleresemblance to their environment. We examine how variousparameters of this formulation allow phototaxis and presentan example of a different, “pathological” behaviour.

  • an active inference implementation of phototaxis
    arXiv: Neurons and Cognition, 2017
    Co-Authors: Manuel Baltieri, Christopher L Buckley
    Abstract:

    Active inference is emerging as a possible unifying theory of perception and action in cognitive and computational neuroscience. On this theory, perception is a process of inferring the causes of sensory data by minimising the error between actual sensations and those predicted by an inner \emph{generative} (probabilistic) model. Action on the other hand is drawn as a process that modifies the world such that the consequent sensory input meets expectations encoded in the same internal model. These two processes, inferring properties of the world and inferring actions needed to meet expectations, close the sensory/motor loop and suggest a deep symmetry between action and perception. In this work we present a simple agent-based model inspired by this new theory that offers insights on some of its central ideas. Previous implementations of active inference have typically examined a "perception-oriented" view of this theory, assuming that agents are endowed with a detailed generative model of their surrounding environment. In contrast, we present an "action-oriented" solution showing how adaptive behaviour can emerge even when agents operate with a simple model which bears little resemblance to their environment. We examine how various parameters of this formulation allow phototaxis and present an example of a different, "pathological" behaviour.