Why do carriers install their version of the OS on phones?

This question has bothered me since a few years back, when I booted up my mother’s phone, only to find that the beautiful XPERIA startup screen had been destroyed by the carrier’s custom boot animation. I had also found a lot of bloatware which could only be disabled, delayed updates, etc. (we all know what’s happening, there’s no reason for me to go in depth).

I searched the web for an answer this question, but to no avail. So, can anyone answer me this:

Why do carriers install their version of the OS on phones and don’t keep the original firmware from the manufacturer untouched?

Because I don’t think it makes any difference for the carriers whatsoever compared to users who get a worse experience.

(Also, let me know if this is a duplicate.)

Database schema for products and their packages

The product is water purifier, and we are selling packages included support for changing filters.

Water purifier type A has many serials so the water purifier that we sold to X has it’s own serial (one serial).

My current solution is like this:

order_product table:

id | order_id | product_id | quantity 1    11          2            2     2    12          103          2 

order_product_services table:

order_product_id | serial    | package_order_product_id 1                  654         2 1                  123         2 

As I think it’s a common problem, what’s the best schema for that?

Does using thorn whip to pull an enemy who is grappling an ally break their grapple on that ally? [duplicate]

This question already has an answer here:

  • Does shoving a creature break its grapple on another? 1 answer

Assuming two medium humanoid types with 5ft reach are the grappler/grappled and the thorn whip pulls the grappler 10ft against their will towards the caster. Does this satisfy the conditions to end a grapple per the final point of the grappled condition, quoted below:

The condition also ends if an effect removes the grappled creature from the reach of the grappler or grappling effect, such as when a creature is hurled away by the thunderwave spell.

List of valuable foders for preventing their deletions

I am writing software that has an option to delete all files is a user-specified directory. This is the usual case for software. For example, cpp compiler has an option to delete all previously generated binaries.

But as far as the user can pass to my program any path, it may appear that he will accidentally remove his home directory together with all its content. Or the content of /etc/bin. Or any other directory that matter, but is not protected by the file system for the current user.

I can check the home directory myself, but I can’t know all possible weak parts, especially in the case when my software is cross-platform. So the question:

Is there exists any list of paths that are not recommended to delete by the user? So I can simply match user input by the pattern and at least warn him.

Heuristic and graphic representation of BV functions and their singularities

This question is about some heuristics and graphs of BV functions.

In 1-dimensional setting, two key examples of $ BV$ functions $ u: \mathbb R \to \mathbb R$ are

  • the Heaviside function, whose derivative is the Dirac delta concentrated at $ 0$ . It is an example of $ BV$ function such that $ Du = D^{jump}u$ .

  • the Cantor function, whose derivative is the Hausdorff measure $ \log_2 3$ restricted to the Cantor set. It is an example of BV function such that $ Du = D^{cantor}u$ .

The graphs of these functions and an intuition on the structure of their derivatives are quite straightforward. And actually, virtually all examples of BV functions I’ve seen in textbooks are 1-dimensional.

However, in the multi-dimensional setting I’m having some difficulties forming an intuition on these matters.

My question has a numerical component and a theoretical component.

  • I’d like to see two nice explicit examples of functions $ u:\mathbb{R}^2 \to \mathbb{R}^2$ which are $ BV$ and have respectively $ Du=D^{jump}u$ and $ Du=D^{cantor}u$ .

  • using computer software like Mathematica or Matlab, I’d like to see the graph of such functions and a plot of their derivatives (so as to also see what the function at the jump set looks like the heuristic meaning of Alberti rank-one theorem on the “direction” of singularities, discussed in two other questions that appeared on MathOverflow Meaning of Alberti rank-one theorem and Alberti rank one theorem and a blow-up argument). I’d also be interested in seeing a representation of the level sets of $ u$ .

If a dagger thrown at a monk splits into multiple daggers mid-air, each with their own attack and damage rolls, can Deflect Missiles deflect them all?


A dagger is thrown at a monk. On that attack, the dagger multiplies into 2 or 3 daggers in mid-air, each dagger with its own rolls for attack and damage. The daggers move one after another such as a line like:

— — —

As a reaction to that one Attack action, can a monk use Deflect Missiles to deflect all of those projectiles, since all of them were thrown on a single Attack action and will be arriving simultaneously?

What happens if an attacker and defender have exactly equal (net difference 0) final values for their attack and defense rolls?

The title somewhat says it all… What happens if an attacker and defender roll exactly equal values? This actually happened to me in a test combat. The other player and I mutually agreed nothing happened.

There’s no entry on the Combat Table for it, this much I know.

How do living politicians protect their readily obtainable signatures from misuse?

Many living politicians’ signatures are found online or can handily be acquired (You can write them, and their letters will contain their signature). Thus do they use a different signature for personal private documents? If not, how can they guarantee that their signatures aren’t replicated without their consent?

I deliberately quote signatures of lesser-known politicians.

The Rt Hon. George Osborne MP

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The Honourable Rona Ambrose PC

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Elaine Chao

Some members of Congress

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