Thats also true for multiple choice tests as opposed to real-world programming.

Or if you are like me (and a bit stupid):

1000 = all possible combinations from 000 to 999.

less 10 combinations with all numbers identical is 990.

now there are three patterns for numbers to be identical left that need to be taken out: 00x 0x0 x00. The x can be replaced with all digits != 0 in this example, so thats 3 (patterns) x 9 ('x' digits) = 27. That times 10 digits that can have double patterns is 270.

1000 - 10 - 270 = 720.

Hmmm. I wouldn't have approached it that way. Thanks for sharing! Lots of ways to approach any problem.

I think he was wrong about the Apple watch market size, but I like his argument.

If economics are irrational because humans are irrational. Apple is the primary argument that humans are irrational.

Forming logical conclusions on anything Apple does is dangerous. They overcharge and under deliver(at least on Hardware). They are primarily marketing, not tech.

For this same reason, their valuation is irrational. I don't expect Apple to be above 500M for much longer than a few years.

So many charts and such a boring conclusion.

Why is the male attractiveness axis flipped in that big blue box? Why is it not mentioned that the turquoise area stretches only on one axis and not the other? Does that mean that super attractive women are more likely to engage with less attractive men than the other way around? I struggle to understand the chart.

Their old data posts (pre-acquisition) were exciting and captivating like short novels with few, but very clear charts. This made me pity professors at uni that have to read uninspired papers and theses at the end of the semester. Sorry.

Thats how it should be I suppose, but can't be taken for granted everywhere.

How is a graph database built under the hood?

I know that a decent RDBMS (simplified) will consist of the following:

- data in blocks organised with a block-size that the underlying filesystem likes

- a cache for the most frequently used blocks

- every index is a B-Tree with pointers to the blocks containing the tuples

Then there are column stores as well as row stores, and for compression you might have some dictionary encoding going on.

Now, how does the Graph Database look under the hood and what are the complexities involved? How is the Graph persisted?

Graph databases are built a lot of different ways; for example Neo4j's architecture is very, very different than something like an RDF triple store, or datastax on top of cassandra.

[Neo4j internals can be seen here](https://www.slideshare.net/thobe/an-overview-of-neo4j-intern...)...it's a bit old but I think mostly still accurate.

In graphs you have to persist nodes and edges, though you may partition nodes by label/category. In the case of neo4j there is a property store rather than a set of columns.

Thanks, very helpful. I am just looking at it and will have a bit of a think about this later :)

A graph database is similar, only it uses direct-record-ids for linking connected entities and not indexes. So instead of doing joins on indexes it follows record-pointers during graph traversals.

In the graph databases book (graphdatabases.com) there is a chapter on the internal architecture of Neo4j.

> how selling TODO lists to businesses is like taking candy from a baby

What does this mean?

It's just my hyperbolic take on the many testimonies I've read by single founders who make SaaS products for businesses and rake in X0,000 per month. And then patio11 shows up and tells them to charge a lot more, so they do, and it works.

"productivity chat market" <-- whats that?

"Work chat"

I had to CTRL+F through the article to learn that PWA == "Progressive Web App".

Am I missing a trend?

I had to do the same, looks like it was coined about a year ago.

https://en.wikipedia.org/w/index.php?title=Progressive_web_a...

This article gives a solid overview: https://alistapart.com/article/yes-that-web-project-should-b...