How can I avoid paying transaction fees?

Is there a way to transfer/import bitcoin from one address to another in order to avoid transaction fees?

No. It is not possible to move btc between addresses without publishing a transaction to the blockchain. However, there are some ways to accomplish a similar result (transferring/altering the ability to spend some coins), but I think every one of those ways will employ a different trust model than actually transacting on the blockchain. As a user, you must balance the level of trust you are comfortable with, against the need to save on transaction fees.

Some examples:

Off chain transactions using a centralized service:

This is how an exchange moves btc between accounts without incurring transaction fees. For example, when you buy/sell on a bitcoin exchange, a transaction is not actually published to the blockchain. Rather, the exchange will simply update their internal database, which keeps a ledger of all user account balances. As a user you are trusting that the exchange has a full reserve of all outstanding user $ and btc balances, and that they will not make an error in keeping track of your account balance.

Off-chain transactions by exchange of private keys

You can give someone bitcoin by simply giving them a copy of private keys for a funded address. In this situation, the recipient will need to trust that you do not own any other copies of the private keys, or that you will not spend the coins yourself if you do have a copy saved.

(as an aside, if you are sharing keys with a friend, and the coins are stolen by a third party, it may be impossible to prove to your friend that you did not simply steal the coins- and vice versa).

Off-chain transactions by exchange of private keys, which are provably not backed up

This is made possible by specialized hardware, such as that produced by OpenDime. In this case, as long as you trust that the OpenDime hardware functions as advertised, you can give someone a funded OpenDime stick and they do not have to worry that you might have a backup of the keys for those coins.

A signed transaction that is communicated off-chain

In this case, you could sign a completely valid bitcoin transaction that sends coins to your recipients address, and then send someone the raw tx data, without publishing it to the blockchain. The recipient would be able to publish the data to the blockchain themselves, but they will have to trust you to not sign and publish a different transaction using those same outputs in the meantime. This method would also only ‘delay’ the spending of the tx fees.

(I’m honestly not aware of any actual use-case for a scheme like this. It’s probably a dumb idea that requires a lot of trust, but it is possible nonetheless)

Payment channels

In this case, two transacting parties can lock some amount of btc into a special multi-sig address, and then trade a limitless number of partially signed transactions back and forth off chain, with no tx fees, and no need to trust the other party will not steal your bitcoin. The parties involved can only exchange value up to a maximum amount (the amount they locked into the channel), but the channel can be bi-directional, so payments can be sent back and forth basically endlessly otherwise. This method still requires a transaction fee to open and close the payment channel, but that fee now account for a vast number of ‘off-chain’ transactions, instead of just one or two on-chain.

An implementation of this idea is the lightning network, it is currently live on the bitcoin testnet.


graphics – How can I avoid seeing fragments of my pre-reboot screen after a reboot?

Every time I reboot my computer, after entering my password and pressing enter, I briefly see jumbled fragments of my screen as it was right before I rebooted. I’m a bit concerned about this from a privacy/security standpoint, as it means that any information that was on the screen when I rebooted is potentially available for someone to see after rebooting. Is there any way I can prevent this from happening, for example by having Ubuntu forcibly clear/overwrite the GPU memory during shutdown?

Note: I don’t use Wayland because of several disruptive issues it has, so I use X11 for both the login screen and my session.

windows – How to avoid Antivirus Firewall blocking?

I just released a game that requires a PC and a mobile phone to communicate via UDP in a local area network. I have a mechanism that adds rules to the Windows firewall for the game.

However, some Antivirus software has blocked the game with its firewall, making it unplayable.
How do I avoid this scenario? Should I contact some of the Antivirus providers? Or, sign our program with a more potent certificate? Or, should I use some of the well-known ports for the game instead?

How to avoid _0 _1 when editing a media entity and changing the file?

Say I add an image using the built-in Media module.

A couple months later, I have to change the image file for some reason. So I edit the media entity, delete the existing file, and upload the new file. The new file has the same name as the old file.

This creates a new file, filename_0.jpg. How can I cleanly replace the file without adding a new suffix?

Oracle – Can I avoid attending the same table three times?

I have this database schema in an Oracle 12c database:

Database schema

I try to answer this question:

In which game did Dallas Mavericks have the largest percentage of successful 3-point shots?

I managed to answer this question with the following question:

SELECT HOME_TEAMS.TEAM_NAME                    "HOME TEAM",
       AWAY_TEAMS.TEAM_NAME                    "AWAY TEAM",
       GAMES.GAME_DATE                         "DATE",
       TEAMS.TEAM_ID                           "GENERIC ID",
       HOME_TEAMS.TEAM_ID                      "HOME_ID",
       AWAY_TEAMS.TEAM_ID                      "AWAY_ID",
       GAME_STATISTICS.X3POINTSHOTS_PERCENTAGE "3 POINTS PERCENTAGE"
FROM GAMES_TEAMS_STATISTICS
         INNER JOIN GAMES ON GAMES_TEAMS_STATISTICS.GAME_ID = GAMES.GAME_ID
         INNER JOIN TEAMS ON GAMES_TEAMS_STATISTICS.TEAM_ID = TEAMS.TEAM_ID
         INNER JOIN TEAMS HOME_TEAMS ON GAMES.HOME_TEAM = HOME_TEAMS.TEAM_ID
         INNER JOIN TEAMS AWAY_TEAMS ON GAMES.AWAY_TEAM = AWAY_TEAMS.TEAM_ID
         INNER JOIN GAME_STATISTICS ON GAMES_TEAMS_STATISTICS.STATS_ID = GAME_STATISTICS.STATS_ID
WHERE TEAMS.TEAM_ACRONYM = 'DAL'
ORDER BY GAME_STATISTICS.X3POINTSHOTS_PERCENTAGE DESC
    FETCH FIRST 1 ROWS WITH TIES;

However, to answer this question, I take part in the team table three times. Can I write this query in any way? in a more efficient way by avoiding so many links ?

Blockchain – how does Bitcoin avoid double spending?

If someone sends Bitcoin with low transaction fees and then sends the same Bitcoin with higher transaction fees before the previous one is confirmed, it's obvious that miners choose the second one

By default, the miner does not select the second one, unless opt-in RBF was activated in the previous one.

Technically or theoretically, however, a miner always has the option of including any transaction in his block template so that he can incorporate such transactions into his block. The only issue is whether his block is widely accepted by the network (including other miners, non-mining full nodes on which the wallet relied, etc.).

ethereum has a nonce value for every transaction that avoids this, but how does Bitcoin avoid this?

I don't know much about Ethereum. As far as I know, the UTXO model itself corresponds to the nonce value, since each UTXO (clearly identified with TXID and output index) can only be issued once, otherwise it is an invalid transaction or an invalid block.


Note that the nonce value / UTXO model and double expenditure by forking the chain are two different problems.

Without the nonce-value / UTXO model, even a single chain cannot rule out double spending or repeated transactions that are actually inflation on Bitcoin or a repeat attack in the Ethereum (the repeated transaction would make the victim another unexpected one arrange for repeated payment so he would lose money).

However, even with the Nonce-Wert / UTXO model, the attacker could create a forked chain to "rewrite history" (in which case the previous transaction would actually be rejected, which generally means that the previous legitimate payment was maliciously withdrawn would be why we need a consensus mechanism like proof of work.

Conditions – Should the Distracted modifier be applied to power rolls to avoid bleeding?

Yes but …

Let's look at the relevant rules. (Emphasis added.)

DRAWN: The hero subtracts 2 from all feature rolls until the end his next round.

And

Bleed out: The injured character dies and has to throw a power at the beginning of it's his turn. Failure means that he dies. He survives with success, but must roll again in the next round (or every minute if not in combat). With an increase he stabilizes and no further throws are required.

(It's worth noting that the end condition changes drastically when Distracted is caused by certain situation rules, especially grappling. However, this is largely irrelevant to the main question, so I won't mention that again.)

If a character is distracted and bleeds to the end, the punishment is distracted still applies for this first roll. The bleeding is done at the beginning the next round while Distracted is expiring the end the next round. howeverIf the character manages to survive this first bleeding bleed, Distracted will disappear.

Other relevant rules:

  • Allies can stabilize the character with a simple (TN 4) healing roll as an action on their own traits.
  • Action cards are still dealt to the character. Partly to determine the turn order and when the character bleeds in the round, but also because it still gets the full benefits of a joker. Including the +2 for all feature rolls.
  • Successfully magical cure also automatically stabilizes the character and eliminates the inability caused by wounds.

C # – Avoid duplicate code between the player and NPC classes that come from Unity's MonoBehaviour

I have a class called players:

public class PlayerFighter : MonoBehaviour
{
    public List Enemies { get; private set; }

    private void Awake()
    {
        Enemies = new List();
    }
}

Then a class called Npc to control all the NPCs in the game (classes like NpcFighter that help the player fight enemies).

public abstract class Npc : MonoBehaviour
{
    (HideInInspector)
    public NavMeshAgent NavMeshAgent;

    private void InitializeComponents()
    {
        NavMeshAgent = GetComponent();
    }

    private void Initialize()
    {
        InitializeComponents();
    }

    private void Start()
    {
        Initialize();
    }
}

This NPC class doesn't necessarily have to take care of enemies as it can itself be an enemy.

But the NpcFighter class will take care of it, how can I allow this without duplicating the enemy list?

public abstract class NpcFighter : Npc
{
    public List Enemies { get; private set; }
}

I could create an abstract fighter class that contains the enemies list, but then I can't get the derived class to use monobehavior and fighter classes as base classes.

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