Absolute maximum occurs at \(f(4) = 5\) because \(f(4) \ge f(x)\) for all value of \(x\) in a domain.
The open dot in the graph indicates that the point is not included in the domain. So, the point \(x = 7\) is not included in the domain. Thus, the minimum value does not occur at the point and hence there is no absolute minimum value.
Since \(f(4) \ge f(x)\) for any \(x\) nearer to 4 in a domain and \(f(6) \ge f(x)\) for any \(x\) nearer to 6 in a domain, local maximum occurs at \(f(4) = 5\) and \(f(6) = 4\).
Since \(f(2) \le f(x)\) for any \(x\) nearer to 2 in a domain, \(f(1) \le f(x)\) for any \(x\) nearer to 1 in a domain, and \(f(5) \le f(x)\) for any \(x\) nearer to 5 in a domain, local minimum occurs at three points such as \(f(2) = 2,f(1) = 3\) and \(f(5) = 3\).