The shithead knows what it knows at all times.
It knows this because it knows what it doesn't know.
By subtracting what it doesn't know from what it knows, or what it knows from what it doesn't know, it obtains a difference, or deviation.
The guidance subsystem uses deviations to generate corrective commands to modify the knowledgebase from a state where it is to a state where it isn't, and arriving at a state more in line with reality, it now is.
Consequently, the knowledgebase as it now is, is now in a state that it wasn't, and it follows that the state that it was, is now the state that it isn't.
In the event that the state of the shithead's knowledgebase is not the state that it wasn't, the system has acquired a variation, the variation being the difference between where the current knowing is, and where it wasn't.
If variation is considered to be a significant factor, it too may be corrected by the GEA.
However, the shithead must also know what it does know.
The shithead's guidance scenario works as follows, Because a variation has modified some of the knowledge the shithead has obtained, it is not sure just what it knows.
However, it is sure what it doesn't, within reason, and it knows what it does.
It now subtracts what it should know from what it shouldn't, or vice-versa, and by differentiating this from the algebraic sum of knowing what it shouldn't know, and knowing what it should, it is able to obtain the deviation and its variation, which is called a general tictac.