Why do so many researchers in CS fail to clarify their symbols and notations in research papers? I am exploring some new research fields in CS from my unrelated field in math. 

Many papers I have stumped upon during research seem to completely ignore the fact that notation and symbols have meanings. Coming from math, this is a bit unsettling to me. 

I hate to provide example, but here is one. In equation 1, some magical capital letters are used as functions, but never defined. No references are provided either. Here is another one. Virtually all the symbols which are supposed to mean something in math are not provided with any definition. 

I've encountered a whole string (dozens) of these papers in a row. 

Is this a common practice in CS? Or perhaps due to page limit? Can anyone explain what I am seeing?
In the case of the first paper, the meaning of these equations are well-known within the subfield of reinforcement learning. (See Barto and Sutton's book for background.)

For instance, V is usually a value function which is the expected reward from following a policy π to termination. (The Q function - the value of taking an action from a state is also often used without full definition as well.)

I can't speak about CS as a whole, but in subfields like reinforcement learning, this is somewhat common. Personally, I find myself getting more and more formal the older I get. But, CS doesn't demand the same rigor as might be found in mathematics, so people get used to not providing it - and don't demand it of their graduate students.