## Using undecidability of the halting problem to show that the function also calls recursively in \$2i\$ if \$i\$ halts

Let $$\{P_i|i = 1, 2, . . .\}$$ be list of all computable functions. For example, $$P_i$$ might be the $$i$$th program and $$P_i(x)$$ would be the output given by that program on input $$x$$.

Suppose that there is an algorithm to decide whether or not a given procedure calls itself.

Consider the procedure $$FUNC(x)$$:

``PROCEDURE FUNC (INTEGER X);       BEGIN INTEGER 1, J;       I ← X DIV 2;       J ← X MOD 2;       IF J = 0 AND Pi(i) halts THEN FUNC (X + l); END ``

How do I use Undecidability to show that $$FUNC(2 ∗ i)$$ calls $$FUNC$$ recursively if and only if $$P_i(i)$$ halts?

## Does casting a spell with the Concentration Tag prevent you from casting any spell, or just spells that also have the Concentration Tag? [duplicate]

• Can I cast a no-concentration spell while concentrating on another? 4 answers

My DM and I were discussing this, and he asked me to search for it/post it here. I looked around, but couldn’t really find anything that discussed this issue specifically.

The description of Concentration is:

Some spells require you to maintain concentration in order to keep their magic active. If you lose concentration, such a spell ends.

If a spell must be maintained with concentration, that fact appears in its duration entry, and the spell specifies how long you can concentrate on it. You can end concentration at any time (no action required).

Normal activity, such as moving and attacking, doesn’t interfere with concentration. The following factors can break concentration:

Casting another spell that requires Concentration. You lose concentration on a spell if you cast another spell that requires concentration. You can concentrate on two spells at once.

The section goes on to outline two more things that can break concentration; Taking Damage, and Dying. It is this first one that we were discussing.

Lets say that I cast Darkness (Which has the Concentration Tag). On my next term can I cast Shatter (Which does NOT have the Concentration Tag), without ending the Darkness Spell?

The wording seems to indicate that you CAN do this, But I’ve had several other DnD Players tell me that you can’t.

## Finding vertex coverage that is also independent set

Given a graph G and integer k, find a vertex coverage set of size k that is also an independent set. I need to either prove this problem is np-complete or find a polynomial solution.

Any idea ?

Thanks!

## Are there any models of operating systems which don’t require rings of privileges, that are also secure?

I am working on a simple operating system in JavaScript and have noticed that there are two kinds of processes: the “main” process (or “kernel” process), and all the other processes. Basically they are implemented completely differently (which makes sense). But I’m wondering if you could reuse some of the logic and just have it all be one type of process. Do any operating systems do this? If so, what do they do? If not, why not?

## Would I still be able to cast conjure barrage if I was also using flame arrow?

Conjure barrage specifies that the ammunition used to cast it must be non magical but I can’t find anywhere if an arrow under the effect of flame arrow is considered magical or not.

What I mean by that is, is the arrow in and of itself magical or does flame arrow just set it on fire as it’s launched as though it had been warped in cloth soaked in oil and lit (but without those steps)?

Would I still be able to use it as a medium to cast the conjure barrage spell or would I not be able to cast that till I lost concentration on flame arrow/the spell ran its course and if not would the effects stack?

## Would an optimization version of the 3-partition problem also be strongly np-complete / np-hard?

Anyone know if an optimization variant of the 3-partition problem (as explained there) would also be strongly np-complete?

This would be where the goal is to group a multiset whose size is evenly divisible by 3 into triplets that sum to as close to a target as possible and to produce this grouping. This would not be a decision problem but an actual optimization problem.

## Do branch – bound and dynamic programming give same solutions for a tsp problem interms of path and cost? , also same number of solutions?

Do branch – bound and dynamic programming give same solutions for a tsp problem interms of path and cost? , also same number of solutions?

## Does casting Inflict Wounds while concentrating on Vampiric Touch also siphon damage?

Vampiric Touch says,

The touch of your shadow-wreathed hand can siphon force from others to heal your wounds. Make a melee spell attack against a creature within your reach. On a hit, the target takes 3d6 necrotic damage, and you regain hit points equal to half the amount of necrotic damage dealt. Until the spell ends, you can make the attack again on each of your turns as an action.

Scenario:

• Round 1 you cast vampiric touch and make a melee spell attack for 3d6 necrotic damage.

• Round 2 while still concentrating on vampiric touch you cast Inflict Wounds as a 3rd level spell for 5d10 necrotic damage.

Being that Vampiric Touch is still functioning, you are making a melee spell attack, and it is dealing necrotic damage… Does the necrotic damage from Inflict Wounds siphon health?

(Obviously the 3d6 and 5d10 wouldn’t stack because of action economy, etc.)

I am sure that a player could find a better use of two 3rd level spell slots, but I have taken up a kind of awkward place as an arcane healer/tank for the group and every bit of preservation helps.

## Do PHP redirect information disclosure also apply to other languages or framework?

When redirecting using `header("Location MyPage.php");` in PHP, any code present after will be executed. So, if you’re using this as a way to avoid user accessing pages where they should be logged in, the content of the page will still be processed and sent to the client. Using a proxy, you can set that despite returning a 302 error code, you’ll also get the content of the page.

My question is, what other languages or framework have this issue ?

## Can I copy prepared Cleric spells that are also on the Wizard spell list into my spellbook?

I’m multiclassing as a Wizard2/Cleric3. I’m wondering if it’s possible to prepare a spell from the cleric spell list and then if it’s also found in the Wizard spell list, would I be able to write it down in my wizard spellbook?

I’m confused by this as the PHB states that if I find a scroll or a book, I can decipher it and boom, it’s in my own book. I’m essentially my own walking book book. I’ve found this in the sidebar in the PHB under wizard regarding spellbooks.

Replacing the Book. You can copy a spell form your own spellbook into another book-for example, if you want too make a backup copy of your spellbook. This is just like copying a new spell into your spellbook, but faster and easier since you understand your own notation and already know how to cast the spell. You spend only 1 hour and 10gp for each level of the copied spell.

If you lose your spellbook, you can use the same procedure to transcribe the spells that you have prepared into a new spellbook. Filling out the remainder of yourspellbook requires you to find new spells to do so, as normal. For this reason, many wizards keep backup spellbooks in a safe place.

Now, lets say that I prepare Protection from Evil and Good, which is a 1st level spell and can both be found in the Cleric spells list and in the Wizard spell list. Shouldn’t it be possible for me to write it down into my spellbook by following the given formula in the “Replacing the Book”; 10gp + 1hour for each level of the copied spell.

I understand that it would have been very different if the holder of the spell I want to copy is another creature (party member or not) but now it’s all me. I know the spells, I own the book, I am the Wizard.