i) Specification
ii) Abstraction
iii) Composition
iv) Decomposition

The order in which the statements are executed may differ from the order in which they are written in the algorithm. This order of execution of statements is known as the control flow.

The data stored in a variable is also known as the value of the variable. We can store a value in a variable or change the value of variable, using an assignment statement.

There are three different types of chameleons: red chameleons, green chameleons, and blue chameleons.

The state is an assignment that changes the values of the variables.

Abstraction is the process of hiping or ignoring the details irrelevant to the task so as to model a problem only by its essential features.

1. --minimum (a,b)
2. -- inputs: a, b are real numbers.
3. --output: result: minimum (a,b)

Model of the action with an assignment statement:
1. --farmer, goat, grass, wolf = L,L.L.L.
2. Farmer, goat:= R, R
3. -farmer, goat, grass, wolf = R.R.L,L
4. --farmer: = L
5. --farmer, goat, grass, wolf = L,R,L.L
6. farmer, grass: = R, R
7. --farmer, goat, grass, wolf = R,R,R,L
8. farmer, goat: = L, L
9. --farmer, goat, grass, wolf = L,L,R,L
10. farmer, wolf: = R.R
11. --farmer, goat, grass, wolf = R,L,R,R
12. farmer: = L
13. --farmer, goat, grass, wolf = L,L,K,R
14. farmer, goat: = R,R
15. -- farmer, goat, grass, wolf = R,R,R,R

An algorithm is a step by step sequence of statements intended to solve a problem. An algorithm starts execution with the input data, executes the statements and finishes execution with the output data.