marvel - Who decides which half of the universe should be destroyed?

Although my question is based on the comic mini-series Infinity Gauntlet issues #1 through 6, I'm open to any and all answers (i.e Movies, other comic books etc. etc.) across the Marvel multi-verse.

It was elegantly presented in the Infinity Gauntlet series how Thanos, after collecting all the soul gems snaps his fingers and destroys half the universe.

Additionally, in the recent movie Avengers: Infinity War,

Thanos does it again! He snaps his fingers and destroys half the universe.

However, one thing is unclear to me. In both cases,

Half the universe is destroyed (or obliterated, or erased from existence).

But who decides which half of the universe should not exist anymore? Does the wielder of the Gauntlet choose, or is the Gauntlet (along with the stones) sentient enough to make the decision?

Answer

It appears to be determined by the wielder

On Titan when Thanos uses the Reality Stone to flashback, he says that his solution to the over population of Titan was a random culling of half the population. A truly random one that would effect rich and poor alike without bias malice.

Later, after his fight with Iron Man, he promises Doctor Strange that:

He would not kill Tony Stark in exchange for Doctor Strange giving up the Time Stone

Obviously,

Once he snaps his fingers, Stark is only one of two survivors on Titan.

The important part being that he survived.

Additionally, Thanos wanted to kill half of any given planet (as seen on Gamora's planet, and again when talking to Stark), not simply half of the universe. This requires a degree of control since not all planets will have the same population count.

So in short, the randomness appears to be true randomness, but this is by conscious design (after accounting for the various other desires of Thanos of course).