Date | November 2017 | Marks available | 2 | Reference code | 17N.2.HL.TZ0.8 |
Level | HL | Paper | 2 | Time zone | no time zone |
Command term | Describe | 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.
Describe an appropriate set of data that could be used to train the network.
State the number of neurons that would be in the input layer.
State the number of neurons that would be in the output layer.
Explain the way in which the output from neuron D will be determined.
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.
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;
Award up to [2 max].
Many sets of digits;
Using different pens/colours/thicknesses etc.;
Written by different people;
900;
10;
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;
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;