Huggett &amp; Wuthrich (2013a) presents a nice overview of the present-day situation as far as the remaining set is concerned. It is worth mentioning that this paper is part of a special issue, Huggett &amp; Wuthrich (2013b), on the emergence of spacetime in quantum theories of gravity. Altogether they discuss and evaluate six types of proposals but we will consider here only three. The remaining three are either too speculative at the present moment or do not involve discrete spacetimes (such as string theory and non-commutative geometry). The three approaches relevant for our topic are: