FIND-S ALGORITHM.pptx
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The Find-S algorithm is a fundamental concept learning algorithm in machine learning that identifies the most specific hypothesis matching all positive training cases. It begins by initializing the hypothesis to the first positive example and generalizes it as needed based on subsequent positive instances. Limitations include its inability to assess hypothesis consistency across data and ignoring negative examples, which can lead to misleading outcomes.
FIND-S ALGORITHM.pptx
- 2. WHAT IS FIND-S ALGORITHM IN MACHINE LEARNING? 2 The find-S algorithm is a basic concept learning algorithm in machine learning. The find-S technique identifies the hypothesis that best matches all of the positive cases. The find-S algorithm considers only positive cases. • When the find-S method fails to categorize observed positive training data, it starts with the most particular hypothesis and generalizes it.
- 3. HOW DOES IT WORK? 3 1.The process starts with initializing ‘h’ with the most specific hypothesis, generally, it is the first positive example in the data set. 2.We check for each positive example. If the example is negative, we will move on to the next example but if it is a positive example we will consider it for the next step 3.We will check if each attribute in the example is equal to the hypothesis value. 4.If the value matches, then no changes are made. 5.If the value does not match, the value is changed to ‘?’. 6.We do this until we reach the last positive example in the data set.
- 4. Find-S Algorithm 4 1.Initialize h to the most specific hypothesis in H. 2.For each positive training instance x For each attribute constraint a, in h If the constraint a, is satisfied by x Then do nothing Else replace a, in h by the next more general constraint that is satisfied by x 3.Output hypothesis h
- 5. Implementation of Find-S Algorithm 5 To understand the implementation, let us try to implement it to a smaller data set with a bunch of examples to decide if a person wants to go for a walk. The concept of this particular problem will be on what days does a person likes to go on a walk.
- 6. 6 Looking at the data set, we have six attributes and a final attribute that defines the positive or negative example. In this case, yes is a positive example, which means the person will go for a walk. So now, the general hypothesis is: h0 = {‘Morning’, ‘Sunny’, ‘Warm’, ‘Yes’, ‘Mild’, ‘Strong’} This is our general hypothesis, and now we will consider each example one by one, but only the positive examples. h1= {‘Morning’, ‘Sunny’, ‘?’, ‘Yes’, ‘?’, ‘?’} h2 = {‘?’, ‘Sunny’, ‘?’, ‘Yes’, ‘?’, ‘?’}
- 7. Limitations of Find-S Algorithm 7 here are a few limitations of the Find-S algorithm listed down below: 1.There is no way to determine if the hypothesis is consistent throughout the data. 2. Inconsistent training sets can actually mislead the Find-S algorithm since it ignores the negative examples. 3. The find-S algorithm does not provide a backtracking technique to determine the best possible changes that could be done to
- 8. 8 Thank You