1. A method of operating a computer, comprising: initiating a first transaction that, in a course of computation, introduces plural transactional memory locations into its read set; during the course of computation of the first transaction, releasing at least one of the introduced transactional memory locations prior to any commitment of the first transaction, the releasing leaving at least one transactional memory location in at least one of the read set and a write set of the first transaction; and during the course of computation of the first transaction, introducing at least one particular transactional memory location into the write set of the first transaction and releasing at least the particular transactional memory location prior to any commitment of the transaction.