Math Problem Statement

Consider a labeled training set shown in figure below:

Suppose that we now find the linear separator that maximizes the margin instead of running the perceptron algorithm.

What are the parameters \theta _0 and \theta corresponding to the maximum margin separator?

(Enter \theta _0 accurate to at least 3 decimal places.)

\theta _0 =-5

\theta =[1,1]What is the value of the margin attained?

(Enter an exact answer or decimal accurate to at least 2 decimal places.)

explain answer in details

Solution

The problem involves finding the parameters θ0\theta_0 and θ\theta corresponding to the maximum margin separator and then calculating the value of the margin attained.

Given: θ0=5\theta_0 = -5 θ=[1,1]\theta = [1, 1]

Maximum Margin Separator

  1. Understanding the Margin: The margin for a linear classifier is defined as the distance from the decision boundary (the hyperplane) to the nearest data point. For a linear separator θTx+θ0=0\theta^T x + \theta_0 = 0, the margin γ\gamma can be expressed as: γ=1θ\gamma = \frac{1}{\|\theta\|} where θ\|\theta\| is the Euclidean norm (or magnitude) of the vector θ\theta.

  2. Calculating the Norm: For the given θ=[1,1]\theta = [1, 1]: θ=12+12=2\|\theta\| = \sqrt{1^2 + 1^2} = \sqrt{2}

  3. Margin Calculation: The margin γ\gamma is: γ=1θ=12=22\gamma = \frac{1}{\|\theta\|} = \frac{1}{\sqrt{2}} = \frac{\sqrt{2}}{2}

  4. Detailed Explanation:

    • The linear separator is defined by the equation θTx+θ0=0\theta^T x + \theta_0 = 0, which can be written as 1x1+1x25=01 \cdot x_1 + 1 \cdot x_2 - 5 = 0 or x1+x2=5x_1 + x_2 = 5.
    • The maximum margin is the perpendicular distance from this hyperplane to the nearest point.
    • The margin is inversely proportional to the norm of θ\theta. Therefore, γ=1θ=12=22\gamma = \frac{1}{\|\theta\|} = \frac{1}{\sqrt{2}} = \frac{\sqrt{2}}{2}.

Thus, the value of the margin attained is: 220.707\boxed{\frac{\sqrt{2}}{2} \approx 0.707}

Summary

  • θ0=5\theta_0 = -5
  • θ=[1,1]\theta = [1, 1]
  • The margin attained is 22\frac{\sqrt{2}}{2}, which is approximately 0.707 when rounded to two decimal places.

Would you like any more details or have any questions?

Here are some questions you might want to ask:

  1. How do you find the Euclidean norm of a vector?
  2. What is the significance of maximizing the margin in SVM?
  3. How does the perceptron algorithm differ from SVM?
  4. Can the margin be negative?
  5. What are the applications of support vector machines?

Tip: When working with linear classifiers, remember that maximizing the margin helps improve the classifier's generalization performance.

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Math Problem Analysis

Mathematical Concepts

Linear Separators
Margins in SVM
Euclidean Norm

Formulas

Margin calculation formula: \( \gamma = \frac{1}{\|\theta\|} \)

Theorems

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Suitable Grade Level

Undergraduate Level