PROBLEM:
Three spies, suspected as double agents, speak as follows when questioned:

Albert: "Bertie is a mole."
Bertie: "Cedric is a mole."
Cedric: "Bertie is lying."

Assuming that moles lie, other agents tell the truth, and there is just one mole among the three, determine:

1.) Who is the mole?

          2.) If, on the other hand there are two moles present, who are they?
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.






SOLUTION:
Bertie is the mole.  Both Albert and Cedric are telling the truth.  Hence, when Albert said, "Bertie is a mole," he was telling the truth, and giving you the correct answer.  When Bertie said, "Cedric is a mole," he was lying, as he himself is a lying mole.  When Cedric responded, "Bertie is lying," he was telling the truth, and also affirming that Bertie was lying.

In the second case, if there were 2 moles, the identifications would be a direct inverse.  Both Albert and Cedric would be moles, and Bertie would be telling the truth