IBM Ponder This #241 · May 2018

We have 11 coins, and exactly two of them are counterfeit with slightly smaller weights than the others. Find the two fake coins using just four weighings of a double-pan balance scale.

Supply your answer as four lines of dash-separated lists of the letters A-K corresponding to the coins.

As an example, here is a solution for the case of seven coins:
ADE-BCG
AG-BE
AC-DG

The first weighing checks coins A,D,E on the left pan vs coins B,C,G on the right side, etc.

Solution

Best opened after a real attempt

To be added.