COGS2010 Lab Week 6
The BackPropagation Network

 

Prior to the session:

At the lab:

 

 

Exercise 1: Randomize the weights and biases. Cycle the network on each of the input patterns in the training set and inspect the activations on the output units. For each individual, record whether that individual is classified as a Jet or a Shark by comparing the relative activation levels of the Jets and Sharks units.

Name

Initial Classification

Robin

 

Margaret

 

Bill

 

Janet

 

Mike

 

Alfred

 

Joan

 

Gerry

 

Catherine

 

Brett

 

John

 

Sandra

 

Joshua

 

Beth

 

Bert

 

Maria

 

 

Exercise 2: Does the untrained network have a classification bias?

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Exercise 3:

Note: Train for 5 (rather than 40 epochs) and report the results after 5 epochs

Use the graph tool to graph the output set error. Change the maximum value that can be displayed in the graph from 1 to 10. Now, randomize the weights and biases of the Jets and Sharks network and then train it for 5 epochs. What is the error on the output set after 5 epochs?

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Exercise 4:

Note: Q 4 has been replaced with the following:

After the network has been trained for 5 epochs, re-test it on the patterns in the training set.  Report which is the most difficult pattern to learn, and explain why

In the following Table, write down the Classification

Name

Correct Classification

Actual Classification

Output Value of winning unit

Robin

Jet

 

 

Margaret

Shark

 

 

Bill

Jet

 

 

Janet

Shark

 

 

Mike

Jet

 

 

Alfred

Shark

 

 

Joan

Jet

 

 

Gerry

Shark

 

 

Catherine

Jet

 

 

Brett

Shark

 

 

John

Jet

 

 

Sandra

Shark

 

 

Joshua

Jet

 

 

Beth

Shark

 

 

Bert

Jet

 

 

Maria

Shark

 

 

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To help you answer the next question, to start off with… tick the appropriate characteristics of each individual.

Name

Gang

Age

Education

Marital Status

Occupation

 

 

20s

30s

40s

JH

HS

C

S

M

D

Psh

Bk

Brg

Robin

Jets

 

 

 

 

 

 

 

 

 

 

 

 

Bill

Jets

 

 

 

 

 

 

 

 

 

 

 

 

Mike

Jets

 

 

 

 

 

 

 

 

 

 

 

 

Joan

Jets

 

 

 

 

 

 

 

 

 

 

 

 

Catherine

Jets

 

 

 

 

 

 

 

 

 

 

 

 

John

Jets

 

 

 

 

 

 

 

 

 

 

 

 

Joshua

Jets

 

 

 

 

 

 

 

 

 

 

 

 

Bert

Jets

 

 

 

 

 

 

 

 

 

 

 

 

Margaret

Sharks

 

 

 

 

 

 

 

 

 

 

 

 

Janet

Sharks

 

 

 

 

 

 

 

 

 

 

 

 

Alfred

Sharks

 

 

 

 

 

 

 

 

 

 

 

 

Gerry

Sharks

 

 

 

 

 

 

 

 

 

 

 

 

Brett

Sharks

 

 

 

 

 

 

 

 

 

 

 

 

Sandra

Sharks

 

 

 

 

 

 

 

 

 

 

 

 

Beth

Sharks