A vote swap is any arrangement where two or more voters commit to pursue any combination of measures for a mutually agreed end. Thus, to swap is a commit verb in this context with implications for the social capital of both.
Thus it is social capital itself that is being traded, and the network reflects a fairly pure distrust mechanism where due processing is required to optimize the swaps. Swaps are not strictly required.
The main purpose of vote swaps is to prevent intolerable outcomes in a first past the post voting system, and almost all swaps are in fact vote pairs between two people, even when there is high demand for swapping into a particular swing district. This is because perceived fairness of swapping multiple votes for one can become very problematic in some legal and political regimes. Also, the incentive for cheating may increase in such circumstances. As such perceptions of fairness are very central in politics (losers must agree to be governed by winners) other non-vote incentives like:
- advocating a particular policy with one's second choice party that received a vote
- informing candidates that one swapped
- donating to the party that loses votes or reimbursement of expenses
are more commonly employed to incent a swap in very unequal supply/demand circumstances, rather than multiple votes by multiple voters. This is technically still a vote pair though the other conditions (some easily verified) make the transaction more of a swap as in finance.