Looks like it was submitted to the joke conference SIGTBD: sigtbd.csail.mit.edu/#home. The conference was April 7, so they were in fact four days early. (Althou

Looks like it was submitted to the joke conference SIGTBD: sigtbd.csail.mit.edu/#home. The conference was April 7, so they were in fact four days early. (Although not publishing on April 1 does seem like a missed opportunity.)