as variables. …… The program form has the structure - (PROG, list of program variables, sequence of statements and atomic' symbols…) …… Program variables
presence of a "magic (reserved) word" in the car position of the form. All non-atomic forms which are not magic forms are considered to be combinations
a mean-field approximation. Instead, there is a critical behavior of the form χ ∼ 1 ( T − T c ) γ {\displaystyle \chi \sim {\frac {1}{(T-T_{c})^{\gamma