Reply #13: It depends on how you set it up...

[MarkusQ]

If, for example, they were required to provide 1) the source code, 2) details needed to compile the code, including compiler version, make files, flags, etc. and 3) copies of the executable code running on the machines, it would be reasonably easy to verify that (1)+(2) --> (3), and that (3) was really what was on the machines.

The bigger problem is that there are many very subtile ways to rig the machines, and it would take lots of eyeballs be sure of spotting them all. True open source code (note to the original poster: "code" is a mass noun, like "salt"--you don't say "open source codes" for the same reason you wouldn't say "pass the salts") tabulators and voting machines would be a very good thing, but it would not prevent tricks that make people stand in the rain for hours, sending people to the wrong polling place, throwing out their ballots, etc., etc.

--MarkusQ