Actually repi didn't say that, it was Thracks. A fellow dev said DX12 programming guide was the same as Mantle though, which is a fair indication of the similarities i think.
You still think it and you question me? AMD say it isn't but you don't want to accept that (for whatever reason) and you are convincing yourself that Microsoft have got Mantle in place to be DX12...
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What part of that makes you think DX12 is Mantle?
And where did the other guy say that Mantle is the same as DX12?