Human skin was devilishly hard to simulate: "It's this crazy landscape of fuzz and squish".
It's so hard to simulate that because there are so many different user cases that you can't simulate in a test environment.
It is unlikely that he will ever need to forage for food, but the rain-or-shine sessions out in the woods taught him independence of a type that is hard to simulate in cultivated environments.
Cloth is hard to simulate yet it's important in gaming, scientific analysis, and CGI.
This makes it hard to simulate the impact of changes in transport costs and transport networks on the trade flows.
Apple, Amazon, and others have worked hard to simulate the experience of reading a book on a tablet computer, device or smartphone.
Multiscale problems such as magnetic reconnection and turbulence are notoriously hard to simulate because the physics of micro and macroscales are strongly linked.
In general, the idea is that there may well be features of human cognition that are particularly hard to simulate, but that are not in any sense essential for intelligence (or thought, or possession of a mind).
It is hard to simulate the charging demand un-constructed by using conventional methods when the real data is absent, which is supposed to be used to provide guidance for charging load assessment of the candidate CS deployments.
The fact that the McKean-Vlasov equations involve an expectation of a certain function under the law of the solution of the equation makes them particularly hard to simulate directly.
