In this video taken at DVCon 2012, Lisa Piper discusses the issue of what happens when unknown values (X’s) propagate through a design and X-optimism can hide bugs and X-pessimism causes unnecessary debug steps

Chris Morrison, Chief Architect at Real Intent discusses the differences
that set the Implied Intent Verification (IIV) tool apart from lint and
simulation. He highlights the positive impact on designs that have
even 99% testbench coverage. This interview took play in July 2012.