It is often stated that the vacuum is trivial when light-front is used, in contrast to equal-time quantization. In fact this is not the case, as has been known since 1969. I give an elementary review of why this happens, and locate an easy-to-miss but elementary mathematical error in proofs of vacuum triviality.
In the light of this, a careful re-examination and reformulation of the mathematics of light-front quantization is needed, and I lay out a program to do this. The program builds on some already-known mathematical complications that are easily overlooked.
(Some of the material in this seminar is in arXiv:1801.03960.)