@rob said in Precinct summability of IRV:
Not sure I understand how that applies. The recount is not affected by the precinct submitting results as they come in. They still have all the ballots they can use for the recount.
Let's say there is a C1V, AV, and IRV election all of which are disputed.
The C1V election has a precinct that reported
A 571
B 482
C 6144
D 16
E 3
F 8
This can be easily checked by hand: sort all the ballots into piles for each candidate.
Now, consider an Approval Voting precinct:
G 883
H 476
I 340
J 181
K 1105
To verify this by hand, you'd need to check all ballots 5 times, since any individual ballot could approve multiple candidates.
Finally, consider an IRV precinct:
L,M,N,O 366
L,M,O,N 68
L,N,M,O 15
L,N,O,M 70
L,O,M,N 4
L,O,N,M 53
etc.
That would involve sorting the ballots into 24 piles to check the totals, or 4 passes through the ballots to check the winner, but if the latter check fails you have a crisis. (For example, suppose the "election night" results are L=50k, M=76k, N=60k, O=L+6. L is eliminated which ends up giving, say, O the victory after N is eliminated. But a recount finds an extra dozen votes for L, so O should have been eliminated first!)
(Actually... verifying the totals may not be as hard as I think. After the L-top ballots are separated, you can verify they add to 366+68+15+70+4+53. Then within the L-top ballots you can verify that 366+68 rank M second, 15+70 rank N second, and 4+53 rank O second.)