DGT boards allow it to be connected with a computer, and thus sending it the moves. WHat algorithm does it use to verify the moves pieces?
This page contains a lot of information about DGT boards, including the patent, detailed description of technologies and algorithms used. Many additional references are provided, too. It is definitely an interesting read!
The board does not verify the moves played at all. It does not even recognize the concept of a "move" - it just tells you where every piece is when you ask for it.