Task 1

In this worksheet, you will explore and construct decision regions of feedforward neural networks (FNNs) with Heaviside activations.

Exercise 1

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Open the tool for Exercise 1

Use the tool and configure the decision region so that the neuron outputs class 1 for all points satisfying

Exercise 2

Open the tool for Exercise 2

Use the following settings:

Step 1

Set the classification mode

Select 2 classes and Single-Label mode.

Settings for a classification task with two classes

Step 2

Configure the graph display

In the graph display, enable Show weights, Show bias values, and Show activations. Set the position to 70%.

Graph display settings

Step 3

Configure the model

Use one hidden layer with a Heaviside activation and select the Heaviside activation for the output layer as well.

Model settings with Heaviside activations

Click the weights and bias values to change them. The FNN should create a red decision region bounded by the following separator lines, as shown in the figure:

FNN with two Heaviside neurons in its hidden layerRed decision region between two separator lines

Exercise 3

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Open the FNN editor for Exercise 3

When the FNN editor opens, the dataset containing bill length, flipper length, and sex is loaded automatically and the decision-region editor is shown. You can also download the CSV file. The column names and class labels in this prepared dataset are in German.

  • Draw four decision regions.
  • Combine two regions at a time into an OR group. Hold Ctrl while selecting the regions.
  • Let the FNN realize the decision regions.
  • Investigate: How are non-convex polygons handled?

Data source and license

Horst, A. M., Hill, A. P., & Gorman, K. B. (2020). palmerpenguins: Palmer Archipelago (Antarctica) penguin data (R package version 0.1.0) Dataset. Zenodo. https://doi.org/10.5281/zenodo.3960218

The original dataset is licensed under CC0 1.0 Universal. For this worksheet, the variables bill length (bill_length_mm), flipper length (flipper_length_mm), and sex (sex) were selected. Incomplete observations were removed, and the column and class labels were translated into German. The derived dataset contains 333 observations.

Download the complete source and license information