An accident happened in a coal mine  The people at the scene concluded as follows: miner 1: the cause of the accident was equipment problem  Miner 2: it is true that someone violated the operation specifications, but the cause of the accident was not equipment problems  Miner 3: if the cause of the accident is equipment problems, someone has violated the operating specifications
Miner 4: the cause of the accident was equipment problems, but no one violated the operating specifications
Miner 1's determination is true.