the percepts are invisible to the protagonist agent. Here, in my invasion example, the belief percepts are produced by an interpreter (I), such as what is depicted in Fig. \[interpreter:1\] and coming indirectly to the defender (D). To be nontrivial, the interpreter is not a kind of a simple mirror or a polarizer. Instead it is another intelligent agent that learns the percepts $ s_i $ by itself and sends what it is learning to the defender as a new state $ b_i $, where the defender percieves them and take actions $ a_i $ on them. As it is assumed in the original paper [@Briegel1], the defender always reaches sooner to the next door than the attacker (here, with or without a stamp from the interpreter).

![image](interpreter1){width="75.00000%"}

Figures \[n\_027000\] and \[n\_227000\] show a reduction in the speed of learning (or learning time) in a partially observable environment (red solid curves) in comparison with a fully observable one (dashed curves) when the interpreter’s forgetting factor is zero. Whereas, we have a reduction in the efficiency of the defender as illustrated in \[n\_127000\] and \[n\_1027000\] when the interpreter’s forgetting factor is not zero. While the reduction in the learning time is 