background preloader


Facebook Twitter

Introduction to A* In games we often want to find paths from one location to another. We’re not just trying to find the shortest distance; we also want to take into account travel time. Move the blob (start point) and cross (end point) to see the shortest path. To find this path we can use a graph search algorithm, which works when the map is represented as a graph. A* is a popular choice for graph search. Breadth First Search is the simplest of the graph search algorithms, so let’s start there, and we’ll work our way up to A*. The first thing to do when studying an algorithm is to understand the data. What is the input? Input: Graph search algorithms, including A*, take a “graph” as input. Sprites by StarRavensee footer for link A* doesn’t see anything else. Output: The path found by A* is . Tradeoffs: For any given game map, there are many different ways of making a pathfinding graph to give to A*.

The pathfinding graph doesn’t have to be the same as what your game map uses. How do we implement this? AIML bot. AIML bot. NeuralNet, Bayesian, SVM, KNN. Continuing from my previous blog in walking down the list of Machine Learning techniques. In this post, we'll be covering Neural Network, Support Vector Machine, Naive Bayes and Nearest Neighbor. Again, we'll be using the same iris data set that we prepared in the last blog.

Neural Network Neural Network emulates how the human brain works by having a network of neurons that are interconnected and sending stimulating signal to each other. In the Neural Network model, each neuron is equivalent to a logistic regression unit. The tuning parameters in Neural network includes the number of hidden layers, number of neurons in each layer, as well as the learning rate. There are no fixed rules to set these parameters and depends a lot in the problem domain. The learning happens via an iterative feedback mechanism where the error of training data output is used to adjusted the corresponding weights of input. Here is an example in R Here is the plot of the Neural network we learn Support Vector Machine. Installing R on Ubuntu.

Once I finally found it, the installation instructions for Ubuntu are less than direct. So, here's how I installed R on Ubuntu 12.04. Firstly get the repository SSL key and import it in to apt. gpg gpg -a Next edit your sources list... gksudo gedit /etc/apt/sources.list ...and add the repository to the bottom. Deb precise/ Then install R. sudo apt-get update sudo apt-get install r-base Now you can get an R prompt with. print("shebang works") Backpropagation. The project describes teaching process of multi-layer neural network employing backpropagation algorithm.

To illustrate this process the three layer neural network with two inputs and one output,which is shown in the picture below, is used: Each neuron is composed of two units. First unit adds products of weights coefficients and input signals. The second unit realise nonlinear function, called neuron activation function. Signal e is adder output signal, and y = f(e) is output signal of nonlinear element. Signal y is also output signal of neuron. To teach the neural network we need training data set.

Propagation of signals through the hidden layer. Propagation of signals through the output layer. In the next algorithm step the output signal of the network y is compared with the desired output value (the target), which is found in training data set. It is impossible to compute error signal for internal neurons directly, because output values of these neurons are unknown. Lenses Classification using neural networks. An example of a multivariate data type classification problem using Neuroph framework Introduction An Artificial Neural Network (ANN) is an information processing paradigm that is inspired by the way biological nervous systems, such as the brain, process information.

The key element of this paradigm is the novel structure of the information processing system. It is composed of a large number of highly interconnected processing elements (neurones) working in unison to solve specific problems. ANNs, like people, learn by example. Neural networks, with their remarkable ability to derive meaning from complicated or imprecise data, can be used to extract patterns and detect trends that are too complex to be noticed by either humans or other computer techniques. Introduction to the problem Neuroph framework will be used to train the neural network that uses Database for fitting contact lenses (Lenses data set).

Procedure of training a neural network Step 1. Step 2. Step 3. Training techniques. ALICE AIML Reference Manual. This document is a "work in progress" Last update: September 01, 2001 Document by: Thomas Ringate Copyright © 2001 Contributing Authors: Dr. Richard S. Wallace; Anthony Taylor: Jon Baer Supported in versions: AIML 01.0 Must be within: an AIML file Can be within: N/A Can contain: <topic><category> Must Contain: could be empty Description: This is the first and last tag of each separate AIML file. Every new file of AIML starts with <aiml version="xxx"> and ends with </aiml>. Example: <aiml version="1.0"> <category> <pattern>*</pattern> <that>WHO IS THERE</that> <template><star/> Who? Supported in versions: AIML 0.9 (This is a deprecated TAG) Must be within: an AIML file Can be within: N/A Can contain: <topic><category> Must Contain: could be empty Description: This is the first and last tag of each separate AIML file.

Supported in versions: AIML 0.9 (This is a deprecated TAG)Must be within:UNKNOWNCan be within: <template> Can contain: nothing Must Contain: nothing or Description: Syntax: R for Statistical Programming Video Tutorials :: Data Mining, Text Mining, neural network, classification, clustering, knowledge explorer, mining. Journal of Statistical Software — Index. MakeAiml Tutorials - An AIML file creation and auto-generation tool for artificial intelligence. Group of Adaptive Models Evolution (GAME) Network Construction on the Iris Dataset. Test Run - Classification and Prediction Using Neural Networks. In this month’s column, I explain how to use neural networks to solve classification and prediction problems. The goal of classification is best explained by example. Suppose you have some historical data about iris flowers that resembles: 5.1 3.5 1.4 0.2 Setosa 7.0 3.2 4.7 1.4 Versicolor 6.3 3.3 6.0 2.5 Virginica 6.4 3.2 4.5 1.5 Versicolor Each line of space-delimited data has five fields.

There are many approaches for classifying data, including the use of neural networks. Figure 1 Neural Network Classification in Action Figure 2 Neural Network Structure After creating the training and testing matrices, the demo program creates a fully connected feed-forward neural network with three input neurons, five hidden neurons for computation and three output neurons. The classification program then loads the best weights and biases into the neural network and evaluates the predictive accuracy of the model on the 20 rows of data in the test matrix. Overall Program Structure The method signature is: Neural Networks with R – A Simple Example | Gekko Quant – Quantitative Trading. In this tutorial a neural network (or Multilayer perceptron depending on naming convention) will be build that is able to take a number and calculate the square root (or as close to as possible).

Later tutorials will build upon this to make forcasting / trading models.The R library ‘neuralnet’ will be used to train and build the neural network. There is lots of good literature on neural networks freely available on the internet, a good starting point is the neural network handout by Dr Mark Gayles at the Engineering Department Cambridge University it covers just enough to get an understanding of what a neural network is and what it can do without being too mathematically advanced to overwhelm the reader. The tutorial will produce the neural network shown in the image below. It is going to take a single input (the number that you want square rooting) and produce a single output (the square root of the input). Onto the code: R Code Example for Neural Networks. See also NEURAL NETWORKS. In this past June's issue of R journal, the 'neuralnet' package was introduced.

I had recently been familiar with utilizing neural networks via the 'nnet' package (see my post on Data Mining in A Nutshell) but I find the neuralnet package more useful because it will allow you to actually plot the network nodes and connections. (it may be possible to do this with nnet, but I'm not aware of how).The neuralnet package was written primarily for multilayer perceptron architectures, which may be a limitation if you are interested in other architectures. The data set used was a default data set found in the package 'datasets' and consisted of 248 observations and 8 variables: "education" "age" "parity" "induced" "case" "spontaneous" "stratum" "pooled.stratum" The following code runs the network (with 2 hidden layers) classifying 'case' (a binary variable) as a function of several independent varaibles.

Nn <- neuralnet( case~age+parity+induced+spontaneous, nn$result.matrix. Category:Reinforcement learning. Confusion Matrix. A confusion matrix (Kohavi and Provost, 1998) contains information about actual and predicted classifications done by a classification system. Performance of such systems is commonly evaluated using the data in the matrix. The following table shows the confusion matrix for a two class classifier. The entries in the confusion matrix have the following meaning in the context of our study: a is the number of correct predictions that an instance is negative, b is the number of incorrect predictions that an instance is positive, c is the number of incorrect of predictions that an instance negative, and d is the number of correct predictions that an instance is positive.

Several standard terms have been defined for the 2 class matrix: The accuracy (AC) is the proportion of the total number of predictions that were correct. It is determined using the equation: The recall or true positive rate (TP) is the proportion of positive cases that were correctly identified, as calculated using the equation: Artificial Intelligence. Artificial Intelligence. Chatbot Battles. Alan Turing Centenary Conference Manchester, 2012 - VideoLectures. During the twentieth century, a number of thinkers - including Kurt Gödel, von Neumann, and Alan Turing - brought the breadth and depth of vision needed to make a number of key breakthroughs.

This was particularly true in the areas of computational science, mathematics, physics, and developmental biology. Important accompanying developments were the building of the first computers; the subsequent use of these computers to simulate human intelligence, the use of mathematics to clarify the limitations and potential of computing machines; the engagement at theoretical and practical levels with simulating and understanding intelligent thought; the modelling of complex processes in nature which appeared to transcend mechanical computation; and the development of a better understanding of how information is created and hidden in the real world. June 23, 2012 marks the centenary of the birth of Alan Turing.

Alan Turing is arguably the most famous computer scientist of all time. The Chatterbot Collection. The Turing Test Page. Mapping Great Debates: Can Computers Think? A must see! 7 large posters that aim to summarize the "Can Computers Think? " debate on nicely structured argumentation maps. Map 2 is on the Turing Test, but all are relevant. These are available online but you cannot read the arguments and links properly. I finally got a chance to see the real maps and liked them a lot. (I almost missed an appointment looking through the chart on the TT...:-)) Coming soon: Want more on the posters? * top * The Turing Test was introduced by Alan M. I propose to consider the question "Can machines think? " Turing Test is meant to determine if a computer program has intelligence. The new form of the problem can be described in terms of a game which we call the "imitation game. " When talking about the Turing Test today what is generally understood is the following: The interrogator is connected to one person and one machine via a terminal, therefore can't see her counterparts.

. * top * NEW! NEW! Stephen J. Mr. AI Zone - AI Forum for chat bot, virtual agent, virtual assistant, virtual human, chatbot & chatterbot developers. 8-Puzzle with A* (A Star) C# Rather than Depth-First, Breadth-First is complete, which means it will find a solution if it exist. But the solution may be so long and we might need to decide which node to expand, which we don't; Assume that we are searching for a node with state 4, with regular BFS, (assuming 2 is the node that will be branching to) we need to create 7 nodes to find the node 4.

But if our algorithm can see that, branching to node 3 at the first point, is better than branching to 2, because if we branch to 2, we will need to create two extra nodes, which means performance loss. But how is an BFS algorithm can decide which node to branch? If an algorithm is able to decide to perform an action than performing another action, it uses a heuristic function. Let's give an example; {0,1,2,3,4,5,6,7,8} is goal state, {1,2,0,3,4,5,6,7,8} and {1,0,2,3,5,4,6,8,7} are states we generated. H({1,2,0,3,4,5,6,7,8}) = 1+1+1+0+0+0+0+0+0 = 3 because there are only 3 piles which are in wrong space. int hval = 0; hval++; </i>*} Sliding Blocks Solver by George Mitsuoka. By George Mitsuoka October 17, 2011 This is my attempt to use the A* algorithm taught in the Stanford online AI class to solve the sliding blocks puzzle. The heuristic function is the maximum of either the number of tiles out of place or the sum of the tiles' distances to their goal positions.

Click on a tile next to the blank to move it into the blank spot. Once you've scrambled the puzzle, click on the "Solve It" button to execute the A* algorithm. After a solution has been displayed, click on the "Execute Solution" button to see it solve the puzzle. Note that some solutions may take a very long time to find. There are sure to be some bugs, especially in the UI. Written entirely in HTML, CSS, and JavaScript, and I don't consider myself a web programmer! I'd be happy to hear any feedback. Solve It Execute Solution Click "Solve It" for solution Idle. Heuristicswiki - N - Puzzle. Heuristics. A*’s ability to vary its behavior based on the heuristic and cost functions can be very useful in a game. The tradeoff between speed and accuracy can be exploited to make your game faster. For most games, you don’t really need the best path between two points. You just need something that’s close. What you need may depend on what’s going on in the game, or how fast the computer is.

Suppose your game has two types of terrain, Flat and Mountain, and the movement costs are 1 for flat land and 3 for mountains, A* is going to search three times as far along flat land as it does along mountainous land. This is because it’s possible that there is a path along flat terrain that goes around the mountains. You can speed up A*’s search by using 1.5 as the heuristic distance between two map spaces. The choice between speed and accuracy does not have to be static. G'(n) = 1 + alpha * (g(n) - 1) If alpha is 0, then the modified cost function will always be 1. Precomputed exact heuristic Multiple goals.

Introduction to Artificial Intelligence - Wolfgang Ertel - Google Books. Artificial Intelligence - Books - Page 2 | InTech Open. E-Books Directory - Categorized Books, Short Reviews, Free Downloads. Artificial Intelligence Books. Intro to AI - Introduction to Artificial Intelligence - Oct-Dec 2011.