The HUGIN App for Bayesian Networks

INTRODUCTION

HUGIN is an easy to use app for building and running Bayesian networks. You can build new and update existing models by adding or deleting nodes, states and links between nodes as well as specifying the conditional probability distribution for each node using a nice UI. The UI implements different gestures to perform certain actions on the model.

You can insert and propagate evidence using the traditional HUGIN message passing algorithm. This ensures fast and correct belief update in the light of evidence. The posterior distribution of each node given evidence is computed automatically without an explicit compilation step.

The app supports Bayesian networks with discrete chance nodes specified in the HUGIN knowledge base (hkb) format. This means that Bayesian networks can be shared with other users as well as opened in the HUGIN Graphical User Interface and Decision Engine. This makes the app a great supplement to these tools.

The HUGIN app is a great tool for learning about Bayesian networks. It can be used by teachers and students interested in the technology that is applied to solve many real-world tasks involving reasoning under uncertainty in artificial intelligence and machine learning.

The app can handle models with up to forty nodes each having as many as eight states. Tables can be as large as 128 parameters with a total size of 2048 parameters.

The HUGIN Editor

The HUGIN Editor enables you to create and edit Discrete Bayesian Network models.
It has HUGIN’s fast inference engine built in which enables you to perform fast and easy probabilistic analysis with your models.

Supported Features

Specifically, the HUGIN Editor supports:

Adding, deleting or moving nodes,
inserting or removing directed edges between nodes,
adding, removing or renaming states on nodes,
editing CPTs,
enter observations on nodes and immediately observe consequent probablity distributions on remaining nodes.

The Network Panel

Gestures for Constructing Networks and Performing Inference

Here is a short introductions to useful gestures in the HUGIN Editor:

Add a node by tapping a single finger on the screen
Evidence is entered on a node by tapping a single finger on the node.
Add or remove a link between a pair of nodes by dragging from the parent to the child.
To enter Node Properies simply double-tap on a node
To move a node, long hold on it and drag it to its new location.
To delete a node, long hold on it and drag it to the trash-can.
To scroll, long hold on the canvas (background) and drag.
To zoom, use the pinch gesture (two fingers).
Shake your device to access undo options.

The Menu

The Menu provides additional options. These are for accessing help, undo/redo or storing your work.
The Menu allows you to:

Help – Access help
Undo – undo the last operation.
Redo – redo the last undone operation.
Save Net – Save the Network with its current name and location.
Name/Move Net – Specify name and location for Network.
Save A Copy of Net – Save a copy of Network to a new location.

More information can be found in the help facilities of Node Properties as explained below.

The Node Panel

Here you can change properties of the selected node.

At the bottom of the screen you see three titles that you can select (Name, States and CPT). Here is a list of useful gestures:

Press the name of the node to change the name of a node.
Press “+” under States to add a state and “X” to delete a state.
Tap on a node state to change its label.
In CPT, press any number you wish to change, the on-screen numeric keypad should appear.

Tutorial Videos

Introduction to Bayesian Networks

Press here for a tutorial on Bayesian networks showing how to build a model (in the HUGIN Graphical User Interface).

For more information on Bayesian network, you may be interested in one of these books:

Bayesian Networks and Influence Diagrams – A Guide to Construction and Analysis (2013) by Kjærulff & Madsen (2013). Springer Verlag, 2nd Edition.

Bayesian Networks and Decision Graphs by Jensen & Nielsen (2007). Springer Verlag, 2nd Edition.

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The HUGIN App for Bayesian Networks

INTRODUCTION

The HUGIN Editor

Supported Features

The Network Panel

The Menu

The Node Panel

Tutorial Videos

Introduction to Bayesian Networks

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