Chapter 8: Support Vector Machines Flashcards

1
Q

describe the idea of support vector machines

A

build a geometric view of separating data points

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2
Q

how do we get the plane in a linear model

A

set boundary equal to 0

i.e.
w1x1 + w2x2 + … + b = 0

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3
Q

how do we calculate the distance between a point and the hyperplane

A

|| w || 2

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4
Q

how do we assign classes in a support vector machine

A

based on whether the distance to the hyperplane is +ve or -ve

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5
Q

how do we calculate the distance from the origin to the hyperplane

A

b / ||w||2

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6
Q

how do we create two parallel hyperplanes

A

set equal +1 and -1

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7
Q

what is the distance between the two parallel hyperplanes

A

2 / || w ||2

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8
Q

what is the separation margin

A

the region bounded by two hyperplanes

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9
Q

what is an optimal hyperplane

A

separates the data points with the widest margin

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10
Q

what are support vectors

A

points that are on the line, The most difficult points to classify

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11
Q

what is done in the process of training an SVM

A

optimise the hyperplane

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12
Q

what does the lagrangian method do

A

a quadratic programming problem that solves the dual problem

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13
Q

what is the dual problem

A

minimising || w ||2 while ensuring all points are outside of the margin

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14
Q

what is a hard margin SVM

A

no points inside the margin

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15
Q

what is a soft margin SVM

A

points allowed inside the hyperplane and on the wrong sides

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16
Q

what is a slack variable

A

relaxes the constrains to allow points into the hyperplane

17
Q

how does a soft margin SVM change the optimisation problem

A

also have to minimise the number of slack variables

18
Q

what are support vectors in a soft margin SVM

A

elements within the margin

elements on the hyperplanes

elements on the wrong sides of the plane

19
Q

how do we support non linear data patterns in SVM

A

kernel method

20
Q

give two kernel methods

A

gaussian

polynomial

21
Q

where is the kernel method added for a non linear SVM

A

in the dual problem

22
Q

what is the decision function

A

how we calculate the optimal values for the multiplies using the results of the dual problem

23
Q

how do we calculate the bias

A

using the slack variables