Difference between subarray, subset & subsequence

Question

I'm a bit confused between subarray, subsequence & subset

if I have {1,2,3,4}

then

subsequence can be {1,2,4} OR {2,4} etc. So basically I can omit some elements but keep the order.

subarray would be( say subarray of size 3)

{1,2,3} {2,3,4}  

Then what would be the subset?

I'm bit confused between these 3.

Answer 1

In my opinion, if the given pattern is array, the so called subarray means contiguous subsequence.

For example, if given {1, 2, 3, 4}, subarray can be

{1, 2, 3} {2, 3, 4} etc. 

While the given pattern is a sequence, subsequence contain elements whose subscripts are increasing in the original sequence.

For example, also {1, 2, 3, 4}, subsequence can be

{1, 3} {1，4} etc. 

While the given pattern is a set, subset contain any possible combinations of original set.

For example, {1, 2, 3, 4}, subset can be

{1} {2} {3} {4} {1, 2} {1, 3} {1, 4} {2, 3} etc. 

Answer 2

Consider an array:

 {1,2,3,4} 

Subarray: contiguous sequence in an array i.e.

{1,2},{1,2,3} 

Subsequence: Need not to be contiguous, but maintains order i.e.

{1,2,4} 

Subset: Same as subsequence except it has empty set i.e.

 {1,3},{} 

Given an array/sequence of size n, possible

Subarray = n*(n+1)/2 Subseqeunce = (2^n) -1 (non-empty subsequences) Subset = 2^n