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In the second step of the category partition technique, the goal is

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to Identify Categories. Where categories are

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characteristics of each input element. So

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let me illustrate what that means using an example. And to do

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that I'm going to use again the example of the split program, as

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we are already familiar with it and we kind of already played

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with it. When we were talking about the generic black box approach.

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So let me bring back the program, and let me remind you

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that what the program does is to take two inputs, a string and

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the size, and it breaks down the string into chunks,

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whose length is size. If we look at the split program

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there are two input elements, str and size so we going to

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identify categories for these two. So starting from str, what are

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the interesting characteristics of the string? In, in this step

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you're going to use your domain knowledge, your understanding of what a

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string is, and for example we might identify the length of

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the string and the content of the string as the two

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main characteristics that we want to focus on. If we now

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move our focus to size, the only characteristic I can really

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think of for an integer is its value. So that's what

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I'm going to mark here. So at the end of the step

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what we have is that we have two categories. So two

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interesting characteristics for the string input str, which are the length

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and the content. And one category for the integer input size

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which is its value. And notice that there's not only one solution.

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So there's not only one possibility.

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So that the specific characteristics that you

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will identify are somehow subjective. But the

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important point is that you identify characteristics

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that are meaningful and they sort of cover the main aspects of the

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inputs, which is the case for the

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categories that we've identified in this example.