There once was a time when if a book said Walter Jon Williams, I would get it, as long as I knew about it and could find it. Some I still have not. I detested Days Of Atonement, however, and though the Dread Empire's Fall book I tried was very average - the same for the short stories related to this series.
A highly eclectic writer, with that much variety an older me now realises that it is extremely unlikely that you will like everything written by a man with such range.
Now we come to Implied Spaces, thanks to Night Shade and Webscriptions, and a great deal bundle.
It would appear that Mr. Williams has set out to again write an uber-science fictional novel. This is in general never a bad thing, to me, at least. If I had to compare this to any of his other work I had read, I would suggest a little of Aristoi, some of Knight Moves, perhaps.
It starts simply, with a man on a research quest encountering bandits, and after a battle involving trolls and black priests (where you could perhaps think you were reading a fantasy book) escalates from there.
The 'Implied Spaces' in the title the protagonists explains as being not necessarily foreseen patterns made when you build something - in this case using an architectural example of a certain type of arch, and what you could see underneath when you look at it. That is pretty mundane compared to this, however, when said Pablo is doing the same thing, but for pocket universes!
There are multiple homages through this book, however, even if you recognise none of them, your enjoyment should not be altered. Or even if you only recognise 'Asimovian protocols' because you know who Asimov is. If you do, however, this should entertain you. Possibly 'Implied Spaces' has a double meaning, in that Williams has maybe inserted this novel into such a spot in the science fiction universe, given the homages and maybe even mashups present within.
There's talking cats, magic in the any sufficiently advanced technology sense swords, immense matrioshka array AI, multi bodies, reincarnation, zombies, and weaponry and conflict that would certainly make Doc Smith and Edmond Hamilton pretty happy.
It is also creepy at times in who Pablo is fighting, what he does to them, and how he (and his allies) go about it. For example, The AIs, with their amazing resources are far in advance of the humans, and do lots of the work for them. However, they have built in limiters that make them do so. Slaves of a sort, in fact, despite being clearly sentient.
Also, he managed to surprise me several times in this book, something I don't find that it is particularly easy to do. Plenty of cool, creepy, confusion and complex to found here in this packed to the rafters sf gem.
I might even go as far as 4.75 perhaps, here.
4.5 out of 5