P(A) = {？ ,{ 1},{2},{3},{4},{ 1,2},{ 1,3},{ 1,4},{2,3},{2,4},{3,4},{ 1,2,3},{ 1,2,4},{2,3,4},{ 1,2,3,4}}。

therefore

R = { & lt？ ,? & gt，& lt{ 1}，{ 1 } & gt； ，& lt{ 1}，{ 2 } & gt，& lt{ 1}，{ 3 } & gt，& lt{ 1}，{ 4 } & gt，& lt{2}，{ 1 } & gt； ，& lt{2}，{ 2 } & gt，& lt{2}、{ 3 } & gt，& lt{2}、{ 4 } & gt。

& lt{3}，{ 1 } & gt； ，& lt{3}、{ 2 } & gt，& lt{3}，{ 3 } & gt，& lt{3}、{ 4 } & gt，& lt{4}，{ 1 } & gt； ，& lt{4}、{ 2 } & gt，& lt{4}、{ 3 } & gt，& lt{4}、{ 4 } & gt。

& lt{ 1，2}、{ 1，2 } & gt； ，& lt{ 1，2}、{ 1，3 } & gt； ，& lt{ 1，2}、{ 1，4 } & gt； ，& lt{ 1，2}，{2，3 } & gt； ，& lt{ 1，2}，{2，4 } & gt； ，& lt{ 1，2}，{3，4 } & gt； .

Too many, and so on, two elements have six lines.

& lt{ 1，2，3}、{ 1，2，} & gt，& lt{ 1，2，3}、{ 1，2，} & gt，& lt{ 1，2，3}，{2，3，} & gt。

& lt{ 1，2，4}、{ 1，2，} & gt，& lt{ 1，2，4}、{ 1，2，} & gt，& lt{ 1，2，4}，{2，3，} & gt。

& lt{2，3，4}，{ 1，2，} & gt，& lt{2，3，4}，{ 1，2，} & gt，& lt{2，3，4}，{2，3，} & gt。

& lt{ 1，2，3，4}，{ 1，2，3，} & gt}。

So I got the answer D.

The fields that discrete mathematics usually studies are: mathematical logic, set theory, algebraic structure, relational theory, function theory, graph theory, combinatorics, number theory and so on. It is one of the important basic courses for computer and related majors in colleges and universities.

This course covers:

Set theory: sets and their operations, binary relations and functions, natural numbers and natural number set, cardinality of sets.

Graph theory: basic concepts of graphs, Euler and hamiltonian graph, matrix representation of trees and graphs, planar graphs, graph coloring, dominating sets, covering sets, independent sets and matching, weighted graphs and their applications.

Algebraic structure: the basic concepts of algebraic systems, semigroups and uniqueness, groups, rings and fields, lattices and Boolean algebras.

Combinatorial mathematics: combinatorial existence theorem, basic counting formula, combinatorial counting method and combinatorial counting theorem.

Mathematical logic part: propositional logic, first-order predicate calculus, resolution principle.

Discrete mathematics is divided into three courses, namely set theory and graph theory, algebraic structure and combinatorial mathematics, and mathematical logic. The teaching method is mainly classroom teaching, supplemented by written homework after class, courseware release through the school network teaching platform and teacher-student communication.