Physical mechanical examples of “M-of-N” locks?

Arbitrary “M-of-N” secret-sharing protocols are a well-studied topic in cryptography, and are apparently so useful that Bitcoin Script devoted a whole opcode to them.

In this blog post, I write:

Suppose we run a bank, and suppose that our bank stores all its gold in one big safe. And suppose that we have three people on our board of directors. We want to ensure that a single unscrupulous director cannot open the safe and steal all the gold. Therefore, we cut three distinct keys, and we craft the safe so that it requires two of these three keys to be inserted simultaneously, in order to open the safe.

Fans of Sean Connery might recognize this as more or less the setup to The Great Train Robbery, except for our “two out of three” requirement. I have not been able to discover any real-world mechanical analogue to the “two-out-of-three” mechanism.

So I ask you!

There is certainly an easy way to construct an “N-of-N” locking mechanism, such that you can get the safe open only when all N keys are inserted. (You just stack the locks vertically down the door, and make sure any single bolt by itself is strong enough to keep the door shut.) “2-of-2” mechanisms are used in bank safety deposit boxes.

I imagine it isn’t hard to construct a “1-of-N” locking mechanism, along the lines of the Borromean rings, but I haven’t found any such mechanisms patented or for sale.

I have not found any references to “M-of-N” locking mechanisms in the real world, nor can I immediately imagine how to construct one (except the brute-force method of obtaining N-choose-M different key safes, each protected by an M-of-M mechanism). Has any inventor ever designed such a physical mechanism? Does any real-world use-case exist for such a mechanism?

Are there any examples in published D&D material of how to destroy a lich’s phylactery?

According to the D&D 5e Monster Manual, regarding destroying a phylactery, it says:

Destroying a lich’s phylactery is no easy task and often requires a special ritual, item, or weapon. Every phylactery is unique, and discovering the key to its destruction is a quest in and of itself.

— p. 203, Death and Restoration

However, no further information is given on how this is typically done, or what is involved specifically.

I get that this is meant as a plot hook for the DM, and that the DM is meant to fill in the blanks as befits their story/campaign, and that the intention here is that different lich’s phylacteries must be destroyed in different ways, rather than a one-size-fits-all method for destroying any phylactery.

However, it would be easier for me to come up with something if I had some examples to work with from existing adventures or additional lore on liches not included in the D&D 5e Monster Manual. Is there anything published in any edition of D&D that describes how to destroy a (specific) lich’s phylactery?

Examples of Analysis of Branch and Bound Method

I am solving a graph problem, which can be formulated as an integer programme. Based on computer experiments, it seems that the branch and bound method works well. I would like to analyse the running time, and wonder whether there have been other problems where branch and bound method was used and the theoretical bounds on the running time has been established?

On another note, if anyone knows any examples of problems where the range of possible values that a variable in a linear programme can take, I’d also be interested in.

In official Pathfinder lore, are there any examples of magic users capable of overwriting rules of magic spells completely?

Are there any magic users that are capable of overwriting magical laws to a degree that would be required to remove any limitations and completely perfect existing spells?

To be clear, I’m looking for a specific example of a caster in Pathfinder lore. Can be an NPC, divine, even a plain old human, anything goes as long as it’s from official lore.

For example, stone shield requires a large amount of earth, so it can’t be used on say a frozen lake. Ice spear melts and thus can’t be used as a permanent barrier save places like the arctic and wouldn’t last very long in hot areas such as the desert. Astral projection has the silver thread. There are very few ways to get around energy resistance short of changing the element. Even something like ignoring components or casting spells instantly would be a major improvement.

Can such a mage exist that is capable of making spells work perfectly with no weaknesses?

What are the examples of a successful DC 30 Ability Check that uses a Skill?

Simply put, are there official examples, such as a table, of DC 30 Ability Checks that use skills, for each skill?

I would like to see what the upper boundaries of a character’s potential is for a skill, but I’m having difficulty finding any references to it.

That is, I understand what Athletics does, but I’m not sure what the maximum potential for an Athletics Check (about 30) would do.

Preferably, I would like to avoid the static/scaling examples in the book, such as how a Dexterity (Stealth) can be contested against a Wisdom (Perception) to be Hidden. These can be applied at any level, and aren’t unique to a DC 30.

Examples of SSL certificates from major vendors

Is there some place I can find example of SSL (TLS) certificates issued by the major vendors, so I can examine them for myself to see things such as what exactly the issuer field says, what signature algorithm is used, etc.?

Obviously I can check the certificate vendors’ own websites, but they tend to use EV certificates, while I’m only looking for a DV one and that will have a different issuer, possibly even a different root CA.

How to make code examples accessible in a document?

I’m creating a MS Word document (and will probably convert it to PDF later on) for a visually impaired programming student.

I’m following all the guidelines about text semantics, like correctly using headers, paragraph, tables, avoiding blank lines, etc. But I don’t know what to do when it comes to code examples. I’m particularly using Python for this document, so not only there are code snippets but also interpreter examples, including the “>>>” symbols. What’s the best way to add these in my document? Should I enclose these examples in a table containing just one cell, and then adding a title to the table along the lines of “this is a code example:”? Should I add line numbers? Any other markup that I should add?

What’s the RPG about a journey from A to B, with examples about French soldiers going to kill Hitler and a team trying to win a TV race contest?

There’s this roleplaying game that’s all about a group of people trying to get from point A to point B.

The two example scenarios that are the base for all the examples in the manual are French soldiers going to Berlin to kill Hitler and guys on a TV game show needing to reach point B to win a prize before a team of hunters catches them.

If I’m not mixing two different games together, the main game mechanic is throwing dice from a certain distance at a target lying flat on a table. Rolling outside the target (too long or too short) or knocking over the pile of dice stacked in the center of the target means failure.

Interface examples for handling “page notes” and highlighted text comments?

I’m working on a collections-based interface (think Pinterest or Dropbox), and we’re implementing a feature that allows users to add Notes/Comments to various elements (folders/boards, files/pages, highlighted text, etc…).

These “notes” would be accessible either via an icon (say, a small Post-It note with the total count), or a sliding tray somewhere (there could be multiple notes for a specific item). Additionally, they’ll need to access any notes they’ve added to specific text they’ve highlighted on a page. Should this be included in the standard Notes, or be treated differently? Not sure…

I’m having a hard time finding inspiration for this, and would love to see examples of Notes being handled really, really well.

Does anyone have any screenshots they could share of existing apps? Or any thoughts on how we should be handling this? I’m a bit stuck here and could use some inspiration 🙂

Thank you so much!