But I think what you're essentially talking about is user reputation - the idea that the opinions of certain people weighs stronger than others. I think there's merit to that.
The upvotes of a person with a high reputation on HN would weigh more than someone else. Reputation could be determined by any number of ways (has authored comments of high value, is manually designated by HN as reputable, has been active in the last N number of days, etc).
The X in my equation accounts for that. You'd need several different deputies to upvote (endorse) a user before it'll deputize them. You couldn't deputize someone on your own.
The Y in the equation means that each deputy would have to have a history of upvoting someone more than once. So you couldn't immediately deputize someone.
There should also be a time limit. Only upvotes cast within Z hours would count in the system. Also, only 1 upvote counts within A hours. This prevents someone from going into a comment history and upvoting past comments.
Even though I think that I'm accounting for cheating, I also believe the system should be hidden from the users. This way no one knows if they've been deputized and they also don't know how to deputize someone else.
"Reputation could be determined by any number of ways (has authored comments of high value"
The trouble with a generic reputation system that values only votes is that it allows for people with any kind of comment (pedantic) to get reputation. My deputy system gives power to a few trusted users and allows that power to slowly trickle down. Hopefully, it'll sculpt the top comments and posts to what PG envisions for the site.