[jeffem]

"One of Ivanov’s losses was in a long game in a closed position (the kind where computers perform poorly)..."

The top computer engines have been strong in closed positions for many years now. If this person did cheat, he most likely was selectively using the engine in this game, or not at all.

There's a reason we don't see computer vs. human matches these days. The computers are too good. You can beat today's elite grandmasters with a free engine running on your laptop.