This is a long question.
The concept of protection is not "defined" officially as far as I know. This makes it quite difficult to discuss since people may have slightly different ideas about what it actually is in precise terms. The article http://www.pokerstrategy.com/strategy/fixed-limit/44/1/ is mostly concerned with when bets for protection should be made.
In a hand evaluation, Dawnfall gives a very useful wording at least. The protection bets fall into two categories; either we root for the opponent to fold when they are given sufficient odd, or we are rooting for them to call given insufficient odds.
We are trying to induce the Sklansky type of "mistakes", those of the Fundamental Theorem of Poker". I mean the type of mistakes that one wouldn't make if one coud see the opponents cards.
So, if we could see the opponents cards, then the absolute majority of bets could be classified as bets for value or protection of either kind. Transparent cards are rare, but something useful and exact can probably be defined in terms of ranges. (This is surely true for the concept of a value bet.)
Here is the question:Is there an existing way of classifying bets more precisely, (preferably exactly) than just saying that value bets and protection bets "go into each other"?
EDIT: A correct definition must assess the probability of the opponents folding or calling with certain parts of their ranges. This is obvious. At a somewhat simpler level, what I'm looking for is a set of rules of thumb - if you see what I mean.
MORE EDIT: Protection does not exist on the river by any sensible definition. It's exact definition on the flop (whatever it is) seems much more difficult than on the turn. Naturally, the number of opponents and their respective types is crucial.
A practical example: Say that I make a 3-bet on the flop is of what I believe is protective nature vs 2 opponents. Suppose that my assesment is wrong, and that I'm not good enough to lay my hand down on later streets because I get sucked in by the pot odds (that I myself create for later streets). Best of all would perhaps be to avoid the protection 3-bet in the first place. In micro limit these things occur often for me unfortunately.
/Johan =