Define and Give examples for a] Boundary Value Analysis b] Equivalence Partitioning c] Error Guessing?

a] Boundary Value Analysis:- It is a test data selection technique in which input data is selected from the input and output boundaries of a given functions. It is a technique that consists of developing test cases and data that focus on the input and output boundaries of a given function.
Example: - Salary should be between 10,000 and 15,000. so test data should be between
Low boundary plus or minus (9,999 & 10,001)
On the boundary (10,000 & 15,000)
Upper boundary plus or minus (14,999 & 15,001)

b] Equivalence Partitioning:-An equivalence class is a subset of data which representative of larger class. Equivalence partitioning is a technique for testing equivalence classes rather than under taking exhaustive testing of each volume of larger class.
Example: - A program which edits credit limits within a given range ($10,000 - $15,000) would have three equivalence classes
Less than 10,000 (Invalid)
Between 10,000 & 15,000 (Valid)
Greater than 15,000(Invalid)

c] Error Guessing
Error guessing is based on the theory that test cases can be developed based upon the intuition and experience of test engineer.
Example:-
Where one of the inputs is date a test engineer may try February 29, 2004 or 9/9/99