That's strange in a number of ways. Obviously you shouldn't have been given that option, but when did this happen? There hasn't even been a unit in Edinburgh for the last few turns.

from Denmark...

I wonder if there is a flaw in the code that would allow a convoy from Baltic to Skag to North to Ediburgh.

I would wager the same sort of thing would happen with A Cons, F Black, Fleet aegean and Cons-Gre being offered to the F Black

Ask xcurlyxfries what he is offered in terms of orders for F North Sea, that might be informative

Ah, thanks Ghost - as you may have noticed I misread that!

Well, I'm not sure why you got that offer, but at least it's slightly logical. After all, the Denmark army could move onto a convoy in the Baltic Sea, but that convoy wouldn't end up in Edinburgh.
I've mentioned the point on the dev forum (http://forum.phpdiplomacy.net)

Why would that help? I'm sure he will rightfully be offered a convoy from and to Denmark.

Oh... but will he be offered a convoy from Livonia... interesting... good point.

I've brought up the more general case that, whilst legal, there is no point offering convoy's to fleets that will never be used. For example, convoy Denmark->Edinburgh should only be offered to the North Sea.
http://forum.phpdiplomacy.net/viewtopic.php?f=3&t=138&p=660#p660

Figle, this is different. Its not a question of whether it WILL never be used, it CAN never be used.

You could offer Den-Edi to F Norweigan, but that is never relevant, is what figle is picking out.

I expect North Sea to be offered Den-Pru/Liv

Are you offered Den-Yor?

I know it's slighltly different Dingleberry, but the whole idea of phpDiplomacy is to be simple for new players to understand, and as such offering useless convoys seems a bad idea.

No valid convoy is useless. You may want to swap two forces positions (one a coastal fleet and the other a coastal army) so you convoy the army around the fleet. Never eliminate valid options, no matter how dumb (like NWS being offered Den-Edi as an option, yes that is truly useless, but valid nonetheless).

I've always wondered why Denmark and Con aren't legally allowed to convoy. They are as much sea/canal zones as they are land zones and that would allow an incredible convoy route from SEV to StP of 17 sea zones (counting the two sea/canal zones).

Actually, it could be done with 18 sea zones!

My guess is that the code just checks all of the territories that could be reached from (start) through all sea spaces with fleets, regardless of the direction. But the code does not take into account any pathfinding used to check that the fleet you're ordering could possibly be on the route in question.

The simplest way to fix this (conceptually) would be to start both the from-territory search and to-territory search operations from the fleet being ordered, instead of basing the latter off of the from-territory selected in the last POST request.

Thanks for pointing this out

The convoy order code constructs a SQL query for finding convoy paths, which makes it really easy to take the code for finding a convoy route and then apply extra criteria.

e.g. If you want to know all the places a fleet can convoy a certain army to you just
- Take the query which finds everywhere that army can be convoyed to
- Add the criteria that the convoy path must include the fleet

This is the code which adds that extra criteria:
http://phpdiplomacy.net/doc/phpDoc/__filesource/fsource_Board_Orders_boardordersconvoyQuery.php.html#a582

The problem with that code is that it didn't bracket properly, so it did:
[blah] OR [blah] OR [blah] AND ( [make sure this fleet is part of the chain] )
When it should have done:
( [blah] OR [blah] OR [blah] ) AND ( [include this convoy as part of the chain] )

I fixed that and Edi was no longer an option, and reran the DATC tests to make sure it didn't break anything

Because the adjudicator uses different code to check convoy paths this was only an aesthetic problem, not an adjudicator bug; assisting a convoy which you can't assist won't affect the outcome, so this'll be added in with the 0.83 update rather than get fixed right away

Thanks again for pointing this one out

I disagree there Draugner. The phpDiplomacy movement input system has been made to make things as simple as possible. I can see the case for allowing you to choose all convoy's, but if so there should be options for all moves and all supports. However, as it stands the code eliminates the confusion invalid orders can cause, and this is surely another case.
Also, I don't see how removing useless convoys would stop you swapping coastal units. To swap A Yorkshire with F Edinburgh, you would convoy via F North Sea. Any other fleet would be ignored and thus doesn't matter.
Anyway, this seems to be what Kestas has corrected, so no problems there.

I agree that the invalid convoys should be removed (and Kestas just fixed it, yes), but I think if the convoy is valid, no matter how useless, you should be allowed to use it. If I want to move from London to Liverpool by going the long way around, I should be allowed to. Heck, If I want to convoy using MAO and NAO (English Channel-MAO-NAO-Irish Sea), that's my right to waste those extra orders. Maybe I am testing the loyalty of an ally by seeing if they will issue a convoy order for me. You can't assume that, because it's stupid for one nation to do it, it has no valid purpose.

Well, that's a decision that's been made from the site. However, if you follow that logic onwards you should allow people to order Bulgaria to move to Clyde. However, that would confuse new players, and so isn't allowed.
However, I think you misunderstand me. I agree London-Liverpool should be allowed either way round. The convoys I was talking of are ones where the more complex version requires every unit for the simple ones. There is no way to convoy from Yorkshire-Edinburgh without having the North Sea as part of it, and as this is the simplest way there is no point offering this convoy to other fleets.

I sort of feel that ANY move should be allowed, even if it's Con supporting a move from Denmark to Tyrolia. The reason I say this is I've been trying to read up on my Gunboat strategy, and it seems that nonsense orders can be a useful tool in the right situations. When I finally got into a Gunboat game I learned that these options weren't allowed on phpDip.

Here is a good example for you...

I have an army at Nor that I want to get to Edi. I have a fleet in the North Sea, and my "ally" has a fleet in the Norwegian Sea. I also have an army in Liv and Yor. I convince my "ally" to convoy from Nor to Edi but he insists I use the North Sea as well (maybe he owns Den and it is open and he doesn't want me jumping on it).

I have the Liv army move to Edi and the Yor army support the convoy to Edi. If my ally tries to jump on Edi, the convoy fails and Liv bounces with him. If he tries to jump in behind at Nor, the convoy fails and Nor stays where it is at. If he does it, the support from Yor guarantees he gets in and, because both fleets were tied up, we both get what we wanted.

So, how useless is that convoy again?

Fig, see above for a valid reason.

I'm with rratclif. If we are going to do gunboat right, invalid orders are a valid way to communicate.

The convoys I think are useless are where there is no way it would be used:
There is no way from Edinburgh to Denmark without passing through the North Sea.
Therefore, for Edinburgh to convoy to Denmark, the north Sea must be one of the units convoying.
Therefore, if there is a longer convoy from Edinburgh to Denmark, the Convoy Edinburgh to Denmark via North Sea must be valid.
Therefore, there is no point offering the longer convoy as it will never be used.
---------
That is my logic from above, hopefully expressed more clearly.
I did not say that multiple convoy options should be removed, just that unnecessary convoys should be hidden.
This is all based on the idea that phpDiplomacy hides useless orders.
If you allow useless orders, which I agree would be very useful in gunboat diplomacy, then the issue doesn't matter, because every unit should be allowed to give every order, even if that means A Budapest orders Convoy Rome->London.

Or perhaps the option to turn on invalid options at game setup? You could even have 'Gunboat/No Press' as a selectable preset, it could turn on invalid orders and turn all communication (or just non-global) off.

Hey, fig, where is the developer forum? I tried to find it and failed, and I feel like this discussion might warrant moving there.

At the very least I would like to see what's being discussed if that's allowed.

http://forum.phpdiplomacy.net/
I mentioned it there, but the discussion rather continued here rather than there, so I continued to post here instead.

Personally, I think there are lots of orders and setup options that should be enabled for people when they start up games, but how this is applied needs to be thought through, because we don't want to scare new users off. I've spoken to Chrispmini's about my idea's on the issue, but I've been working primarily on making a better orders interface, and so haven't had time to work on this.

To that effect, could you say something like "Gunboat/No Press", "invalid options", etc. only allowed after 5 (or some #) games completed?

figle: To avoid scaring new users and have more experienced users set up "more comlicated" options like no press / public press only / ... just have these options accessible under an "advanced options" button when setting up games (that might even only show up after 5 completed games or above 100 points).

That is my view as well, although I personally think that as long as you add a suitably detailed explanation panel along with this there is no need to block it from new users. There are a long list of options I'd like to add, but as I say, at the moment I don't have the time to write it in.

But the assumption that the longer one from Edinburgh to Denmark would never be used is invalid itself. Now, if there i sno fleet in North Sea then, yeah, eliminate the option from the list, but as long as there are multiple paths, even if they use one or more of the same sea zones, all paths must be made available. Take my example, but configure it for Den to Edi. Maybe Norway is the open one for your ally and he is also in the North Sea, so he insists that you use your Norwegian Sea fleet along with his North Sea fleet to get to Edi so you can't hit his empty Norway. There is always the possibility of a valid reason to use it. Only eliminate those that can't be done (no fleets in the sea zones for instance).

Unfortunately, that latter one comes down to the way the adjudicator is implemented, rather than how the available moves are generated. kestas has chosen to implement the multiple paths as follows-- as long as at least one path exists from origin to destination (among the fleets that haven't been dislodged) the actual convoy path does not matter.

So in Draugnar's situation just detailed above, the Norwegian Sea ally could renege and the convoy would still go through, because A Den-Edi on this site never specifies exactly how the army should get there.

If you look at the DATC tests page you'll see that there are in fact certain discussions about various adjudicator implementation choices. kestas has made his choice, and it's not likely he'll change the adjudicator to force people to specify convoy paths (the PHP and MySQL queries would get a lot more complicated).

Ah: That would explain why what I said didn't make sense. I thought that was understood - sorry I stated the same view twice then!
Personally, I am in favour of this application, and if I remember rightly this is also the view stated in the DATC itself (although I must admit I haven't checked it recently)

Grrrr... I hadn't noticed that limitation in the UI. Can you tell I'm used to playing on the Judges where you specifiy your convoy route. This technique allows for intercepting and disrupting a convoy. Now, an enemy fleet or two that could make a valid convoy could act to convoy the army and that enemy's ally could intentionally dislodge the fleet and interrupt it. Hmmmm...

Or would the convoy still succeed using the alternate path?

Rereading Katsarephat's post, it sounds like the alternate path would just be taken if one of the fleets not crucial were dislodged.

To be clear, prior to the 1982 rules, a convoy was disrupted when one possible path was disrupted. So, ordering an additional convoy, made the convoy weaker.

In the 1982 rules this has been changed. All possible paths must be disrupted for disrupting a convoy.

The rules prior to 1982 are very problematic to implement. A foreign fleet, that is likely to be dislodged, could order a convoy for possible disruption. The DPTG has all kinds of additional rules to counter this effect. With the 1982 rules (and later) these problems cease to exist. Given the fact that additional convoy paths give in most cases no tactical advantage (a support is often better), this is a great simplification (and so improvement) of the rules.

The convoy path specification of the judges/DPjudge has never been part of any rules.

There are a few unclear parts in the rules, but this issue is not one of them.

Lucas

More interesting are detours.

Suppose there is a fleet in:
- Gulf of Lyon
- Western Mediterranean
- Tyrrhenian Sea,

Then you order a convoy for all fleets from Marseilles to Naples.

There is a path that includes the Western Mediterranean, but it is more a detour than alternative path, because you go directly from Gulf of Lyon to Tyrrhenian Sea.

So, there is no path where Western Mediterranean is necessary.

Should it appear in the list? It is a little tricky to program that correctly, because the fleet must be unnecessary for all possible paths.

Lucas

Assuming this fix is effective now, it didn't work. My Baltic fleet can convoy FROM Denmark to EDI, York, London, all the way to Tunis, North Africa and Gascony.

If I convoy the unit in Prussia, I cannot get him to London, etc.

Dingleberry:

Said kestas, earlier:

"Because the adjudicator uses different code to check convoy paths this was only an aesthetic problem, not an adjudicator bug; assisting a convoy which you can't assist won't affect the outcome, so this'll be added in with the 0.83 update rather than get fixed right away"

So just don't worry about it and don't be stupid with your convoys and you should be fine.

Ah, misread his post.