This could be a truly historic election.

For the first time in the history of Northern Ireland, the head of government could be a nationalist.

Since its creation just over a century ago, political unionism has dominated here.

In practical terms, the offices of First and Deputy First Minister are one and the same.

They are joint heads of government; they discharge their duties jointly; and one can't exist without the other.

Symbolically, a nationalist First Minister would be seismic. As much a historic political breakthrough for nationalists as a political and psychological setback for unionism.

But the result might not be straightforward. There could be two winners in this election.

The expectation is that Sinn Féin will emerge as the largest party in Northern Ireland for the first time.

But this is not first past the post, it’s a PR - proportional representation - election and transfers mean being top of the pile doesn’t necessarily translate into most seats in the Assembly.

So Sinn Féin could emerge with the votes and the most seats. Top party on both counts.

Or it could be top of the votes pile but the DUP could once again emerge with more seats.

The party that gets to nominate the First Minister is the one with the most seats.

So in this scenario, Sinn Féin would be the largest party in terms of first-preference votes, but the DUP largest in terms of seats.

What if they tie, say 25 seats each ?

In that case the party with most first preferences is the winner and nominates the First Minister.

Unless, that is, one of them can persuade another Assembly member to designate themselves as a member of their party before the new Assembly meets for the first time, which is expected to be next Thursday.

In that scenario, they would then have 26 seats and could appoint the First Minister.

Most of the discussion about this unlikely, but not impossible, scenario centres around Independent candidate Alex Easton in North Down.

He was elected as a DUP member of the Assembly in 2017 but left it last year.

If there’s a tie and - as expected - he’s re-elected, he could be the king maker for the DUP if the party could persuade him to come back into the fold.

What if Sinn Féin beats the DUP by one seat and Alex Easton was persuaded to rejoin the ranks and take it to a draw?

Independent Unionist Alex Easton may play a role in deciding who becomes First Minister

In that case, first-preference votes are the deciding factor and the party who has the most of these gets to appoint the First Minister.

But here’s the rub. As Alex Easton is standing as an independent, the first preferences he gets could not be added to the DUP total.

So he could only possibly come into play if the parties are tied when the final results are declared.

Straightforward, eh?

Welcome to the political world of Northern Ireland.