Nitpicking:

'Ο' is used for an estimate in excess (it's supposed to be a capital omicron, not an 'oh')

'Ω' is used for an estimate in defect (o-mega "is bigger" than o-micron)

'Θ' is used for the actual growth.

For example: mergesort is Ω(1), Ο(n²), Θ(n log n)

This is important since it's quite common to know boundaries on the complexity, but not the exact complexity. For example, matrix multiplication is Ω(n²) (you have to generate all the elements), and surely Ο(n³) (there is a naif algorithm with that complexity), but we don't know the exact function.

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        dakkar - Mobilis in mobile