As mentioned, P is a subset of NP, and the intersection of NP and NP-hard is NP-complete.
The oval-shaped box would be one if P= NP= NP-complete.
If P=NP were proved true, there would be many serious real-world consequences. All known encryption schemes rely on the fact that prime factors of large numbers are something that can be feasibly verified but not calculated. If P=NP, that means there would also be feasible ways to calculate prime factors, and hence de-crypt codes without their private keys.
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