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Date November 2017 Marks available 3 Reference code 17N.2.HL.TZ0.8
Level HL Paper 2 Time zone no time zone
Command term Explain Question number 8 Adapted from N/A

Question

Artificial neural networks (ANNs) are being used in a variety of applications, including pattern recognition, game playing, classification and data mining.

An ANN is being trained to recognize handwritten numbers by identifying them as a digit from 0 to 9.

Assume that each digit to be identified is input as an image made up of 30 × 30 pixels.

A simplified version of an ANN is shown below.

Explain one reason why ANNs are suitable for solving the types of problems found in these areas.

[3]
a.

Describe an appropriate set of data that could be used to train the network.

[2]
b.

State the number of neurons that would be in the input layer.

[1]
c.i.

State the number of neurons that would be in the output layer.

[1]
c.ii.

Explain the way in which the output from neuron D will be determined.

[3]
d.

The network is set up with initial values. The outputs are compared with the desired outputs.

Identify the steps that now take place to train the network.

[5]
e.

Markscheme

The functions/mathematical relationships in these types of problems;
Which are required for use with traditional algorithms/non-ANN algorithms;
And are difficult/impossible to define;

a.

Award up to [2 max].
Many sets of digits;
Using different pens/colours/thicknesses etc.;
Written by different people;

b.

900;

c.i.

10;

c.ii.

Award up to [3 max].
The product of;
The weights and the input values;
Will be summed for neurons A, B and C;
From this will be subtracted a bias/constant / This will be compared to a bias/constant/ A function will be applied;

d.

Award up to [5 max].
The difference between the actual and desired outputs;
Which is the value of the cost function;
Leads to adjustments in the weights;
Of the neurons in the hidden layer(s);
The process is repeated;
Until the cost function reaches an acceptable value;
Or a certain number of iterations are made;

e.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.i.
[N/A]
c.ii.
[N/A]
d.
[N/A]
e.

Syllabus sections

Option B: Modelling and simulation » B.4 Communication modelling and simulation
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Option B: Modelling and simulation

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