I was going through ID3 algorithm, and what I believe is it incorporates Greedy Search rule to get come up with the decision tree. If it gives the best split possible at every stage, how does it not give the best decision tree possible?

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    $\begingroup$ It's a local optimum, not a global one. All tree building algorithms are merely heuristics. $\endgroup$ Oct 5, 2018 at 10:24
  • $\begingroup$ If you want the best decision tree, you need the "optimal decision tree", which you can get nowadays. Just have a look into the vast literature. $\endgroup$ Oct 10, 2020 at 9:17
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    $\begingroup$ Greedy algorithms only rarely guarantee a globally optimal solution. $\endgroup$
    – Ben Reiniger
    Nov 9, 2020 at 15:32
  • $\begingroup$ Can you name a better algorithm than ID3 for a single tree? $\endgroup$
    – Nathan B
    Jun 12 at 17:47


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