Forking in model theory is a dependence relation defined from inconsistency along indiscernible parameter sequences. A formula 
divides over a parameter set
when there is an 
-indiscernible sequence 
beginning with 
for which 
is inconsistent. Indiscernibility means
that increasing finite subsequences of the same length satisfy the same formulas
over 
.
A formula forks over 
when it implies a finite disjunction of formulas that
divide over 
.
A type forks when it contains a forking formula. Here the type of a tuple over a
parameter set is the collection of all formulas over
that set satisfied by the tuple.
In stable and simple theories, nonforking supplies an abstract notion of independence. The stable forking conjecture asks whether forking in a simple theory always has a witness given by a stable formula.
