COMMUTE

To exchange substantially; to abate but not abolish completely, a penalty, obligation, or payment in return for a great, single thing or an aggregate; to cash in; to lessen

"to commute tithes into rentcharges for a sum; to commute market rents for a premium, to commute daily fares for a season ticket"

Of an operation, to be commutative, i.e. to have the property that changing the order of the operands does not change the result.

"A pair of matrices share the same set of eigenvectors if and only if they commute."