In both $$AST$$ and $$CFG,$$ let node $${N_2}$$ be the successor of node $${N_1}.$$ In the input program, the code corresponding to $${N_2}$$ is present after the code corresponding to $${N_1}$$

For any input program, neither $$AST$$ nor $$CFG$$ will contain a cycle

The maximum number of successors of a node in an $$AST$$ and a $$CFG$$ depends on the input program

Each node in $$AST$$ and $$CFG$$ corresponds to at most one statement in the input program

make parsing and semantic analysis simpler.

improve error recovery and error reporting.

increase the chances of reusing the machine-independent code optimizer in other compilers.

improve the register allocation.

In statically typed languages, each variable in a program has a fixed type

In un-typed languages, values do not have any types

In dynamically typed languages, variables have no types

In all statically typed languages, each variable in a program is associated with values of only a single type during the execution of the program