Not math: in the planned ePBS upgrade, a committee of 512 validators per slot reports whether a block's contents arrived on time.
Why it matters: The upgrade only works if most of that committee is honest.
On the map: a majority of its 512 members reports payload arrival truthfully (ePBS, not cryptographic)
Not a cryptographic assumption. With ePBS, builders commit to a block's contents first and reveal the payload afterwards. A payload-timeliness committee of 512 validators per slot votes on whether the payload showed up on time[1].
ePBS assumes a majority of that committee reports honestly. Otherwise builders could be unfairly penalized or rewarded.
If any of these breaks, this breaks too.
If this breaks, these break with it.