100 Prisoners' Names in Boxes

The following puzzle is a variation of the above puzzle.

Names in Boxes

• The names of 4 prisoners are placed in 4 wooden boxes , one name to a box, and the boxes are lined up on a table in a room. The boxes are numbered 1,2,3 and 4.

• The names are randomly placed. Therefore, box 1 is equally likely to contain the name of any of the 4 prisoners. Same is the case for the other boxes.

• One by one, the prisoners are led into the room; each may look in at most 2 boxes, but must leave the room exactly as he found it and is permitted no further communication with the others.

• Each prisoner, before entering the room, needs to call out which 2 boxes they will open. They can then open only these 2 boxes.

• The prisoners have a chance to plot their strategy in advance, and they are going to need it, because unless every single prisoner finds his own name all will subsequently be executed.

• What strategy can they use to maximize their survival ?