Ciro Santilli @cirosantilli 37

As per en.wikipedia.org/w/index.php?title=Semidirect_product&oldid=1040813965#Properties, unlike the Direct product, the semidirect product of two goups is neither unique, nor does it always exist, and there is no known algorithmic way way to tell if one exists or not.

This is because reaching the "output" of the semidirect produt of two groups requires extra non-obvious information that might not exist. This is because the semi-direct product is based on the product of group subsets. So you start with two small and completely independent groups, and it is not obvious how to join them up, i.e. how to define the group operation of the product group that is compatible with that of the two smaller input groups. Contrast this with the Direct product, where the composition is simple: just use the group operation of each group on either side.

Product of group subsets

So in other words, it is not a function like the Direct product. The semidiret product is therefore more like a property of three groups.

The semidirect product is more general than the direct product of groups when thinking about the group extension problem, because with the direct product of groups, both subgroups of the larger group are necessarily also normal (trivial projection group homomorphism on either side), while for the semidirect product, only one of them does.

Conversely, en.wikipedia.org/w/index.php?title=Semidirect_product&oldid=1040813965 explains that if $G=N⋊H$, and besides the implied requirement that N is normal, H is also normal, then $G=N\times H$.

Smallest example: $D_6=C_3⋊C_2$ where $D$ is a dihedral group and $C$ are cyclic groups. $C_3$ (the rotation) is a normal subgroup of $D_6$, but $C_2$ (the flip) is not.

Note that with the Direct product instead we get $C_6$ and not $D_6$, i.e. $C_3\times C_2=C_6$ as per the direct product of two cyclic groups of coprime order is another cyclic group.

TODO:

Bibliography: math.stackexchange.com/questions/1726939/is-this-intuition-for-the-semidirect-product-of-groups-correct

The finite element method is one of the most common ways to solve PDEs in practice.

Open source driver/hardware interface specification??? E.g. on Ubuntu, a large part of the nastiest UI breaking bugs Ciro Santilli encountered over the years have been GPU related. Do you think that is a coincidence??? E.g. ubuntu 21.10 does not wake up from suspend.

Arghh, why so hard... tested 2021:

Great set of long distance routes.

They are very well chosen for their high safety and level interest, so you can just go into them without putting much thought into it.

Sometimes they go a bit too much on the side of safety, making certain transitions annoying, but in general the selection is spot on.

The routes do sometimes go on a bit of gravel, so they are most adequate for hybrid bikes rather than road bikes, although road bikes would be able to to much of them. A more road-bike dedicated possibility is the The National Byway.

Note however that there are many many other local routes which are not in the network, but arguably equally, or more worthwhile.

Their diginal map distribution mechanisms are a bit shitty and sometimes asks you to pay for certain formats, which is hard to understand given that the maintainer of those maps, the Ordnance Survey appears to be public... github.com/cirosantilli/cirosantilli.github.io/issues/61 "How to see the Sustrans National Cycle Network on Google maps?"

Googling "National Cycle Netowrk KML" leads to: data-sustrans-uk.opendata.arcgis.com/ from which we can download the KML. gis.stackexchange.com/questions/216770/how-to-open-kml-file-in-google-maps-for-android then shows how to make that viewable on Google Maps by going through www.google.com/maps/d/u/0/?hl=en on the browser. TODO 2021-11:"Ralph Hughes" www.linkedin.com/in/ralph-hughes-501474121 is listed as the creator/responsible of the exports, but can't find his email. Sent an email to gissupport@sustrans.org.uk and he did reply a few days later that they are aware of the issue, and are particularly trying to reach out to Google about it. Great news!
GPSPrune 20.2-1 can open the KML however, so that file can't be entirely wrong.

OpenStreetMaps has them on by default though if you just click "Cycle Map" layer. It is not as incredibly detailed as the Ordnance Survey one, e.g. does not show which side of the street to ride on, but still, is very good.

According to www.baseten.co/blog/nvidia-a10-vs-a10g-for-ml-model-inference/ the Nvidia A10G is a variant of the Nvidia A10 created specifically for AWS. As such there isn't much information publicly available about it.

Official page: www.nvidia.com/en-gb/data-center/tesla-t4/

According to wccftech.com/nvidia-drops-tesla-brand-to-avoid-confusion-with-tesla/ this was the first card that semi-dropped the "Nvidia Tesla" branding, though it is still visible in several places.

Ciro Santilli's account is www.reddit.com/user/cirosantilli/, see also: accounts controlled by Ciro Accounts.

Transaction retries are inevitable, as some sQL isolation levels

Doesn't seem to have any simple built-in mechanism?

First Amazon hire, wrote and led the team that wrote v1.

He looks like an older and more experienced dude compared to Bezos at the time.

Bibliography:
. www.geekwire.com/2011/meet-shel-kaphan-amazoncom-employee-1/2/ also mentions that unlike California, there's no sales tax in the state of Washington, which is important for selling books.