A 2010 entry by the same author:

Markets are efficient if and only if P = NP https://arxiv.org/abs/1002.2284

In a P=NP world, it still takes only one uninformed participant to make the market inefficient. I don't think the implication is bidirectionally true unless you assume every single player is rational, infinitely smart, and has access to the same set of information.

	▲	samrus an hour ago \| parent [-]
		Its game theory so perfect play is assumed. Spherical cows and all that

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Dibby053 2 hours ago | parent | prev | next [-]

So markets can only be (perfectly) efficient or competitive, not both at the same time. Largely theoretical but it tracks common sense!

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ffsm8 2 hours ago | parent [-]

The title on this HN submission is just wrong. Click on the link and find out.

	▲	seizethecheese an hour ago \| parent \| next [-]
		The title is wrong but you’re also wrong. Read the abstract of the paper. Here’s the relevant section: > Combined with Maymin (2011), who proved that market efficiency requires P = NP, this yields a fundamental impossibility: markets can be informationally efficient or competitive, but not both.
	▲	abejfehr 2 hours ago \| parent \| prev [-]
		isn't that what they're saying with "not both at the same time"? the papers both have opposite signs, one has != and the other has =

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p-e-w 2 hours ago | parent | prev [-]

Assuming the original result is correct, isn’t the linked paper simply a corollary?

	▲	2 hours ago \| parent \| next [-]
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	▲	philipwhiuk 2 hours ago \| parent \| prev [-]
		The newer paper expands on the work of the former.