Making graph acyclic by removing back edges in depth first and breadth traversal

I came across following points:

  1. Removing all back edges produced by DFS makes the graph acyclic.

  2. For a directed graph, the absence of back edges with respect to a BFS tree implies that the graph is acyclic.

There was no explanation given for first point. But explanation for second point was as follows:

It is true that the absence of back edges with respect to a DFS tree implies that the graph is acyclic. However, the same is not true for a BFS tree. There may be cross edges which go from one branch of the BFS tree to a lower level of another branch of the BFS tree. It is possible to construct a cycle using such cross edges (which decrease the level) and using forward edges (which increase the level).

However I am unable to get the explanation. I believe back edges are essential for forming cycles as can be seen in below image (black edges are breadth first tree edges, green is back edge, red is cross edge and dashed edges form cycle):

enter image description here

As we can see, removing back edge can lead to disconnecting cycle.

Q1. So how solution says we can form cycle only with the help of cross and tree edges?

Q2. If 2nd fact is indeed correct, then how the same does not apply to fact 1, that is why we cannot prepare cycle without back edges in depth first traversal.

Is there any intuitive way to see the validity of these statements and answer my questions?

Why is a host making requests for WPAD file from external location?

In NGFW logs of my customer, I noticed requests to [REDACTED]/wpad.dat being made. Destination domain is registered on an external IP not related to the customer and user agent suggests that Windows AutoProxy is used. I was able to download the wpad file myself and inspect its contents:

function FindProxyForURL(url, host)   {   return "DIRECT";   }  

If I understand correctly, the traffic is not routed through any rogue proxy server for it to be a WPAD attack.

I’m trying to figure out what could have caused this traffic to take place to begin with? “Internet settings” changes (made by e.g. malware) on the hosts? And are there any other risks related to this traffic, aside from the fact that the wpad file can be changed by the server owner?

What’s the legality of making a character editor?

I want to develop a character editor for role-playing games. At first just for one game, but I want to expand it later to cover multiple games.

What laws (like copyright and intellectual-property) do I have to consider, and what is allowed in it and what isn’t? What are my limits without a contract with the game’s publisher? Is there a difference between free, commercial, and open-source character editing software software?

I am aiming at Shadowrun 5 first.

How to stop players from making the game X-rated

After 30 years, a few of my friends and I finally managed to get together and play D&D. We’ve managed to play 2hrs once a week for the last 6 weeks.

I unfortunately ended up being the DM. My problem is that the players, in spite of being given an obvious quest and hooks into multiple possible adventures, seem completely uninterested in doing anything other than sleeping with every NPC.

It’s not just Ingsaw the Tiefling Barbarian sweeps Lady Winsome off her feet and carries her to the bedroom where they spend the night. They want graphic details of every act. Also the two women players are just as bad as the three guys.

At the beginning of the last session, I even said that I was uncomfortable with the X-rated content our game was generating. I declared that starting with that session that any hint of having sex with an NPC would stop at the first lewd line and then be boiled down to a persuasion attempt and if successful a d20 roll, 1-5 horrible, 6-10 forgettable, 11-15 ok, 16-20 time of your life and that would be all the details I would give. After a couple attempts to see if I was going to stick to it, the session was spent with the player’s characters sleeping with each other. About half way though I got up from the table and spent the rest of the time puttering around the kitchen until everyone eventually left.

I realize the last time any of us played we were about 14 and this may be the way they remember D&D (although I don’t). Or maybe we’re all over 40 and this is the only way their sexual fantasies are going to ever happen. Regardless I don’t want it in the game. Since these are all friends I need a polite way of getting through to them. After last session I’m not sure what to do other than start cancelling at the last minute until everyone gives up on coming.

Update: I sent basically the suggested email in the answer I accepted. While it didn’t prevent all drama and hard feelings, at least it is over, they’re going to continue SexyTimes while I go find another group, and most importantly we’re all still friends.

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I'm a bit of financial situation and decided to sell my hard worked business web services. I push my life to complete this site. I personally this web service got very big potential now and for the future and there will always people who need it as long there is Internet.

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Why am I not making any money?

I have a computer ten million times as powerful as the ultra-expensive mainframes/supercomputers of decades past. It’s already 5+ years old and takes minimal space. It’s a Raspberry Pi.

Other than that, I have a massively powerful PC. It has a database software installed and I have the ability to program/script it. I could technically design all kinds of intricate software systems which could in theory make me rich.

But I’m not. I’m not making one damn cent.

Why is this?

What am I missing? Why are these ultra-powerful, amazing machines worthless in the year 2020? I have never felt more powerless than I do now. I feel like a lowly peasant in the year 1200 or something. I have as much power as they did, in spite of my sci-fi-like, “magical” machines and my programming/scripting/database design knowledge.

I think I’m going out of my mind.

Prevent an application from making any network access on macOS

I want to run an application on macOS, but preventing it from making any type of network access, or any type of internet access.

I have seen the following possibilities:

  • Use the built-in firewall. Unfortunately, this blocks only inbound connections, not outbound.

  • I have seen Little Snitch. However, it feels uncomfortable from a security standpoint to install a closed-source software on my system that has so deep an access to everything I do.

Ideally, I would like to do that myself. Is it possible to restrict an app’s access to network ressources on macOS ? Maybe start it in a sandbox mode somehow?


How much times the strength modifier does a chained barbarian add when making a bite using Animal Fury?

The assumption is bite is the only attack the barbarian makes during the turn, and the barbarian has no other natural attacks. I seem to get three different answers on this:

The barbarian adds 0.5x the strength modifier. This is because the rules on Animal Fury state that “If the bite hits, it deals 1d4 points of damage (assuming the barbarian is Medium; 1d3 points of damage if Small) plus half the barbarian’s Strength modifier.”

The barbarian adds 1x the strength modifier. This is because the 19 STR cannibal from the gamemastery guide has its bite damage listed as 1d4+4, which is consistent with this.

The barbarian adds 1.5x the strength modifier. This is because a bite is a primary natural attack, and the natural attack rules state that “If a creature has only one natural attack, it is always made using the creature’s full base attack bonus and adds 1-1/2 times the creature’s Strength bonus on damage rolls.”

So which one is it?

How to resolve fundamental differences in perspective between players and DM about the roles each has in decision making?

To give context: I am a DM running a D&D 5e campaign set in a home-brew setting for the better part of a year. A few months ago I suggested having an alternate “gaiden” style campaign set in the same setting in which the same set of characters go on short adventures with rotating DMs that could be used during sessions where some players were not available to play. During this winter holiday, one of my players was unable to make sessions and I implemented this system with myself taking the first turn as DM. All players were given invitations to the campaign and given character sheets on our role play app, including the non-available player. The adventure was expanded as the players came to enjoy the narrative and I had new ideas, and is now reaching towards its conclusion. My absent player recently became available again and expressed interest in joining in this campaign. I said yes, some members of the group said no.

While the exact argument was long and circuitous with some hurt feelings, the basic salient points from each side were:

Against Joining

  • Inclusion of new members of the campaign are group decisions.
  • Introducing new characters towards the end of the campaign disrupts the narrative.
  • By making an executive decision under DM purview from the get go, I am undermining their perspectives and feelings by “laying down the law” and not listening to their side. (This might be true.)

For Joining

  • The player is part of the pre-existing group and is not a new member as this adventure is an extension of main campaign.
  • While players are encouraged to add to the narrative, what is and is not narrative appropriate falls under the domain of the DM as stated on pages 5 & 6 of the 5e Players Handbook.
  • Additionally, I have interesting narrative plans involved with his character, that several players and DM’s outside of this group approve of.
  • As the DM, I serve as referee. As I view this player as a pre-existing group member, it comes under my purview to make judgement calls how certain player on player issues are resolved. This has been the case before when other players had issues with class abilities overlapping over each others roles and could not come to a compromise, and certain players having issue with role-play issues overshadowing other players. In both cases I had to make official DM statements to resolve the issue.
  • As a DM I have a prerogative to enjoy myself during these sessions else I lose interest in the game and it dies. Excluding a player who I see as part of the group who has done nothing wrong do to what I feel is pressure from a large minority of players does not sit right with me and would impede in my enjoyment.

In the end, I said that I will not exclude anyone member of the group at the behest of the others for what I see as a non-issue, and several player were upset with this decision, seeing it as inappropriate, with at least one player leaving the group outright.

So how do I this resolve fundamental differences in perspective between players and DM about the roles each has in decision making? Am I in the right for making the decision I did? If so, how do I resolve this group dynamic issue? If not, how do I repair these ingresses?