Incorporation of Cultural Phenomena--论文代写范文精选

发明一个新想法,电流复制到神经网络的输入层,而这之前的行动作为基础来生成一个新的层次。为每个节点代理来决定是否会发生变化。如果是这样的话,代理学习指定的新想法并实现了行动。下面的paper代写范文进行阐述。

Abstract 
In addition to knowledge-based operators, discussed previously, agents incorporate the following phenomena characteristic of cultural evolution as parameters that can be turned off or on (in some cases to varying degrees): 
• Imitation. Ideas for how to perform actions spread when agents copy neighbors’ actions. This enables them to share effective, or ‘fit’, actions. 
• Invention. This code enables agents to generate new actions by modifying their initial action or a previously invented or imitated action using knowledge-based operators (discussed previously). • Mental simulation. Before committing to implementing an idea as an action, agents can use the fitness function to assess how fit the action would be if it were implemented.

MAV allowed only worlds that were toroidal, or ‘wraparound’. Moreover, the world was always maximally densely populated, with one agent per cell. In EVOC the world can be either toroidal or square, and as sparsely or densely populated as desired, with agents placed in any configuration. EVOC also allows the creation of complete or semi-permeable permanent or eroding borders that decrease the probability of imitation along a frontier.

Each iteration, every agent has the opportunity to (1) acquire an idea for a new action, either by imitation, copying a neighbor, or by invention, creating one anew, (2) update the knowledge-based operators, and (3) implement a new action. To invent a new idea, the current action is copied to the input layer of the neural network, and this previous action is used as a basis from which to generate a new one. For each node the agent makes a probabilistic decision as to whether change will take place. If it does, the direction of change is stochastically biased by the knowledge-based operators using the activations of the SYMMETRY and MOVEMENT nodes. Mental simulation is used to determine whether the new idea has a higher fitness than the current action. If so, the agent learns and implements the action specified by the new idea.

To acquire an idea through imitation, an agent randomly chooses one of its neighbors, and evaluates the fitness of the action the neighbor is implementing using mental simulation. If its own action is fitter than that of the neighbor, it chooses another neighbor, until it has either observed all of its immediate neighbors, or found one with a fitter action. If no fitter action is found, the agent does nothing. Otherwise, the neighbor’s action is copied to the input layer, learned, and implemented. Fitness of actions starts out low because initially all agents are immobile. Soon some agent invents an action that has a higher fitness than doing nothing, and this action gets imitated, so fitness increases. Fitness increases further as other ideas get invented, assessed, implemented as actions, and spread through imitation. The diversity of actions initially increases due to the proliferation of new ideas, and then decreases as agents hone in on the fittest actions.

Summary of Previous Results
EVOC closely replicates the results of experiments conducted with MAV (Gabora, 1995). The graph on the bottom left of Figure 2 shows the increase in fitness of actions. These results show that concepts from biology are useful in the analysis of cultural change, but that culture also exhibits phenomena that have no biological equivalent. Previous work on EVOC focused on the effects of changing the need, and integrating multiple needs (Gabora, 2008). It was found that changing the need (modeled as a change in the fitness function) or giving agents multiple needs to fulfill, does not change the overall pattern of results. Mean fitness of actions still increases gradually, and diversity of actions rises and then falls, exhibiting the typical inverted U-shaped curve, the magnitude of which is a function of population size. However, increasing the number of needs consistently results in a higher diversity of actions, and tends to decrease mean fitness with respect to any given need.(paper代写)

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