Do my opponents get a penalty to see me if I sneak up from behind?

My friends and I started a Dragon Age Roleplay and in the situation “A rogue approaches a creature from behind,” we must test the creature’s sight against the rogue’s dexterity. An argument arose that the creature doesn’t receive a penalty for facing the other direction. The GM said that it’s not written in the rules, while I think that it’s only natural for a penalty in the opposing check.

Can someone help me with that argument? Does the creature get a penalty, or not?

How does Disarming Assault interact with the Multiple Attack Penalty?

A barbarian has picked up the `Disarming Assault` feat. He uses it as hit first action.

1. Does the `Strike` increase his `Multiple Attack Penalty`?
2. If the `Strike` increases his `Multiple Attack Penalty`, does the `Athlectics` check to `Disarm` suffer the increased `Multiple Attack Penalty`?
3. Does the `Athlectics` check to `Disarm` increase his `Multiple Attack Penalty`?
4. What is his total `Multiple Attack Penalty` after using `Disarming Assault`?

PF2: blind when fighting – what is the penalty?

What happens when an enemy is blinded and wants to fight? What penalty does the enemy get when he wants to attack?

Is the enemy flat footed?

How does haste interact with the heavy armor penalty?

For a character that is wearing heavy armor, but does not have the prerequisite strength, there is a 10ft speed penalty.

If the Armor table shows “Str 13” or “Str 15” in the Strength column for an armor type, the armor reduces the wearer’s speed by 10 feet unless the wearer has a Strength score equal to or higher than the listed score.

Haste doubles the speed of the person it was cast on.

Until the spell ends, the target’s speed is doubled

Since the movement speed of heavy armor is a fixed amount, does the doubling apply to the base speed or the current speed? ie. A human with a base speed of 30. They put on heavy armor and have their speed reduced to 20. Haste is cast on them, does their speed become 30*2 – 10 = 50 or (30-10)*2=40?

Can you avoid the stress penalty of Wish by using Astral Projection?

The wish spell is likely the most powerful and risky spells in Dungeons and Dragons. However, using it to do anything other that duplicate spells carries stress (and potentially losing the spell forever). Below I have quoted the relevant information:

The stress of casting this spell to produce any effect other than duplicating another spell weakens you. After enduring that stress, each time you cast a spell until you finish a long rest, you take 1d10 necrotic damage per level of that spell. This damage can’t be reduced or prevented in any way. In addition, your Strength drops to 3, if it isn’t 3 or lower already, for 2d4 days. For each of those days that you spend resting and doing nothing more than light activity, your remaining recovery time decreases by 2 days. Finally, there is a 33 percent chance that you are unable to cast wish ever again if you suffer this stress.

However, I want do know if these risks carry over to your mortal form, if you were under the effects of astral projection. Below I have quoted the relevant information:

Your astral body resembles your mortal form in almost every way, replicating your game statistics and possessions.

Your astral form is a separate incarnation. Any damage or other effects that apply to it have no effect on your physical body, nor do they persist when you return to it.

So would casting wish while under astral projection subject your body to stress and possibility of losing the spell wish, after astral projection has ended?

If a character has the TWF feat from 3.5 and the Ambidexterity feat from 3.0, does this remove the TWF penalty?

I’m not exactly sure how these would stack if they were both allowed. Would the -2/-2 with a light weapon and TWF be eliminated or would it be exactly the same (thus making Ambidexterity obviously redundant)?

If I am hiding and moving silently at the same time, what is my total movement penalty?

In D&D 3.5, according to page 79 of the PHB under the move silently skill:

You can move up to one-half your normal speed at no penalty. When moving at a speed greater than one-half but less than your full speed, you take a –5 penalty.

And, according to page 76 of the PHB under the hide skill:

You can move up to one-half your normal speed and hide at no penalty. When moving at a speed greater than one half but less than your normal speed, you take a –5 penalty.

Assuming:

• I have no special abilities that have any relevance to this circumstance

• I am able to move silently and hide in the same round

• I wanted to do this without incurring a penalty on my skill checks

• My normal movement speed is 30ft

Would my speed, which I have opted to reduce, be to 15ft or would it be 7.5ft?

What is cold-start penalty ? What are some ways to reduce it?

when a new process is created using a fork() function, there is a cold start penalty, what is this and why does it happen?

How can ideas like Lagrange Multipliers and Penalty Method be applied for solving algorithms?

I have a programming assignment which I was told that is solvable with some DP algorithm. The question involves some $$k$$ which is essentially a constraint. In particular the question is a variant of LIS problem where at most $$k$$ exceptions (restarts) are allowed.

But I know that there is a better solution. My professor mentioned Lagrange Multipliers and giving a penalty for each restart. But after googling these terms I wasn’t able to find out something related to algorithms. I read about them on Wikipedia but I can’t figure out how to use them. Also every article is related to Calculus and function optimization.

Is there a keyword that can describe better what I want to read about?