Combination: Combination means selection of things. The word selection is used, when the order of things has no importance.
There are also two types of combinations (remember the order does not matter now):
Repetition is Allowed
No Repetition
Permutation: Permutation means arrangement of things. The word arrangement is used, if the order of thingsis considered.
There are basically two types of permutation:
Repetition is Allowed
No Repetition
Here is an example to understand more about the Combinations and permission with & without repetition: below is a simple search screen contains various types of materials and list of contractors.
Select one or more checkboxes from material and select a contractor then click search button to display the records. Any test engineer will design couple of test cases or do adhoc testing (in one or two ways) on the screen and then simply say done.
Actually the following ways must be done to ensure the screen is tested thoroughly.
One member combination with no repetition
Machine, Parts, Sub Parts (contractor should go with each material) – 3 cases
Two member combination with no repetition
{Machine, Parts} {Machine, Sub Parts} { Parts, Sub Parts} (contractor should go with each material) – 3 cases
Three member combination with no repetition
{Machine, Parts, SubParts} (contractor should go with material) – 1 case
If sequence is important to select the material and contractor
One member permutation with no repetition
Machine, Parts, Sub Parts (contractor should go with each material) – 3 cases
Two member permutation with no repetition
{Machine, Parts} {Machine, SubParts} { Parts,Machine} { Parts, SubParts} { SubParts,Machine} { SubParts, Parts} (contractor should go with each material) – 6 cases
Three member permutation with no repetition
{Machine, Parts, SubParts} {Machine, SubParts, Parts} { Parts,Machine, SubParts} { Parts, SubParts,Machine} { SubParts,Machine, Parts} { SubParts, Parts,Machine} (contractor should go with material) – 6 cases
Combi.exe will helps to generate results in three ways: a)Combinations b)Permutations c)Possibilities
For example, let us say materials 1 (Machine), 2(Parts) and 3(Sub Parts) were chosen. These are the possibilities:
Order does matter Order doesn't matter 1 2 3 1 2 3 1 3 2 2 1 3 2 3 1 3 1 2 3 2 1