The Two General's Problem

penny wrote:And if the drunken and shameless wiki is correct about a projected 100 LDs, then that means the MAN can position 100 LDs right above the Queen’s head and sit. Laugh. Talk. Give someone a birthday party. Not be discovered. And not worry about being discovered. All while waiting for orders to attack!

I'm not even finding where the wiki claims 100 ships. The Lennard Detweiler-class page just say

drunken wiki wrote:With twenty-eight Shark-class training ships having been successful, a far bigger number of Leonard Detweiler-class units were planned to be built

(claiming that comes from SftS). And a check of the history shows it never claimed a specific number of LDs.

However even that vague "far bigger number" appears to be a misinterpretation of the text. Because here's what SftS actually says

Storm From The Shadows wrote:Substantially larger units with far more magazine space were on the drawing board, designs based in no small part on the experience Benjamin and his crews had acquired working with the ships currently under Topolev's and Colenso's command. Some of those larger units were already entering the first phases of construction, for that matter. And, again, Albrecht wished they'd been able to wait until those larger ships were available in greater numbers.

"in greater numbers" appears to be in reference to the "some" which were beginning construction -- not to the twenty-eight Shark class. And even if it was intended to compare LD numbers to Shark numbers there's a vast gulf between "in greater numbers" (which could be just a few more) and in "far bigger numbers"

So I'm not sure where the 100 ship number came from; but it doesn't seem to be from the obvious spot in the wiki; and in any case doesn't appear to have any textual evidence in the books.

penny wrote:I was under the impression that navies gathered way out in the boondocks in an uninhabited system so as not to be discovered. A navy can’t gather in hyper in a system’s backyard waiting to attack.

Yes it can, if it remains in hyper. See the above point about the PN in OBS. In that case, the RMN was barely defending Basilisk, but commercial traffic wasn't low.

That is not true of the MAN. The MAN can gather in an inhabited system way above their head "looking down on the underlings." Navigation won’t be a problem to frequently traveled systems like the MBS, etc. And they certainly won’t have a problem finding their way back home. They would have mapped that region themselves for decades.

In hyperspace? This goes against what we're told by the author. The Junction is probably the single most travelled cubic light-minute in the entire Galaxy, and yet both commercial and military navigators were making mistakes all the time. If it were possible to "map the region" in hyper, that wouldn't be happening. We're told that the only way to navigate in hyper is using the hyperlog, which is effectively an inertial navigation system.

There's an apparent internal contradiction here: the hyperlog is so precise that most navigation arrives within a few light-seconds of any location they desire to arrive. And yet, hyperspace meet ups seems to be impossible. My guess at explaining this is that one doesn't design military operations that require meeting up in hyper, because the chance of hyperlog imprecision sending them just too far to meet is too high, something like 1 in 20.

As for meeting in n-space, we've discussed to exhaustion. Transiting six light-months out isn't "gathering in the MBS" but instead "gathering in interstellar space." And with no nearby "landmarks," I'm not sure how well you could orient yourself in case the hyperlog was imprecise.

In any case, as you've yourself said: anyone can do this. The only thing the MAN can do differently is arrive much closer to a target system and fly in completely stealthily, though the target system may be aware they're coming.

True. And don’t forget that it can be eaten by a giant amoeba. Thus, that is why all solutions to The Two Generals’ Problem always include a second messenger. There will always be two messengers.

Sure, redundancy. But again: anyone can do this.

Gasp! First. No need to worry about any of that if the DB travels in an exclusive band. I’m surprised you’re using that as an argument since all of you are so fixated on removing even the unlikeliest things that can happen like a giant amoeba. In fact, it amuses me that all of you would think that the chances of an HV ship actually failing without removing the safety interlocks is greater than Tester intervening and slapping the DB all the way back to Darius space! And we’re talking about relatively new ships.

Yes, so long as it's an exclusive band, the chance of a random encounter is actually zero, not practically zero like for everyone else. However, I'm making the argument that the use of hyper, in any band, is close enough to "exclusive band" that there's effectively no difference. Especially if you're not taking a well-travelled route anyway, which you shouldn't be because you're going to somewhere that no one else goes to.

But you are missing the size of the advantage. It isn’t simply about the chances of a DB being intercepted while traveling in hyper’s lowest bands. Which -- as all of you have consistently pointed out -- is non-zero.

Mathematically I agree: a non-zero chance is infinitely larger than a zero one.

But for practical purposes, I am claiming that it is effectively the same.

It is about the massive fleet that can gather and throw a party and not worry about being discovered. A massive fleet that has gathered right above the enemy’s head! Do you all realize that the MAN can assemble its entire Home Fleet right above Manticore’s head? Not light years away in some uninhabited system!

Yep, and so can everyone else and have as much chance of meeting up, per the rules we've heard of in the HV. There are two issues here: one is that being "slightly away" in hyper effectively means "undetectable," so anyone can gather a fleet a light-minute outside of any target and be effectively undetected - though not zero. The other is that the ability to gather forces is chancy - for this, you have to travel in formation. That means a fleet could loiter waiting for the time to attack, but it can't be met by a DB coming from elsewhere with the orders to attack.

As often as an army catches a messenger trying to tiptoe through their camp in the dead of night. That is what this thread is about. It is a dead giveaway. No pun intended.

Bad analogy. Again: per the rules of the HV, no one is patrolling hyper and the random encounter chance is effectively nil. So unless the enemy knows to search for a DB coming and knows where to search for it, it won't find the DB.

It happened to the Havenites when they thought they were tiptoeing through Pavel Young’s camp. Only to find out the Mother of all Loose Warheads had replaced him and figured out there was a fleet waiting in hyper to attack.

In n-space, not hyper.

ThinksMarkedly wrote:

penny wrote:I was under the impression that navies gathered way out in the boondocks in an uninhabited system so as not to be discovered. A navy can’t gather in hyper in a system’s backyard waiting to attack.

Yes it can, if it remains in hyper. See the above point about the PN in OBS. In that case, the RMN was barely defending Basilisk, but commercial traffic wasn't low.

That is not true of the MAN. The MAN can gather in an inhabited system way above their head "looking down on the underlings." Navigation won’t be a problem to frequently traveled systems like the MBS, etc. And they certainly won’t have a problem finding their way back home. They would have mapped that region themselves for decades.

In hyperspace? This goes against what we're told by the author. The Junction is probably the single most travelled cubic light-minute in the entire Galaxy, and yet both commercial and military navigators were making mistakes all the time. If it were possible to "map the region" in hyper, that wouldn't be happening. We're told that the only way to navigate in hyper is using the hyperlog, which is effectively an inertial navigation system.

There's an apparent internal contradiction here: the hyperlog is so precise that most navigation arrives within a few light-seconds of any location they desire to arrive. And yet, hyperspace meet ups seems to be impossible. My guess at explaining this is that one doesn't design military operations that require meeting up in hyper, because the chance of hyperlog imprecision sending them just too far to meet is too high, something like 1 in 20.

As for meeting in n-space, we've discussed to exhaustion. Transiting six light-months out isn't "gathering in the MBS" but instead "gathering in interstellar space." And with no nearby "landmarks," I'm not sure how well you could orient yourself in case the hyperlog was imprecise.

In any case, as you've yourself said: anyone can do this. The only thing the MAN can do differently is arrive much closer to a target system and fly in completely stealthily, though the target system may be aware they're coming.

True. And don’t forget that it can be eaten by a giant amoeba. Thus, that is why all solutions to The Two Generals’ Problem always include a second messenger. There will always be two messengers.

Sure, redundancy. But again: anyone can do this.

Gasp! First. No need to worry about any of that if the DB travels in an exclusive band. I’m surprised you’re using that as an argument since all of you are so fixated on removing even the unlikeliest things that can happen like a giant amoeba. In fact, it amuses me that all of you would think that the chances of an HV ship actually failing without removing the safety interlocks is greater than Tester intervening and slapping the DB all the way back to Darius space! And we’re talking about relatively new ships.

Yes, so long as it's an exclusive band, the chance of a random encounter is actually zero, not practically zero like for everyone else. However, I'm making the argument that the use of hyper, in any band, is close enough to "exclusive band" that there's effectively no difference. Especially if you're not taking a well-travelled route anyway, which you shouldn't be because you're going to somewhere that no one else goes to.

But you are missing the size of the advantage. It isn’t simply about the chances of a DB being intercepted while traveling in hyper’s lowest bands. Which -- as all of you have consistently pointed out -- is non-zero.

Mathematically I agree: a non-zero chance is infinitely larger than a zero one.

But for practical purposes, I am claiming that it is effectively the same.

It is about the massive fleet that can gather and throw a party and not worry about being discovered. A massive fleet that has gathered right above the enemy’s head! Do you all realize that the MAN can assemble its entire Home Fleet right above Manticore’s head? Not light years away in some uninhabited system!

Yep, and so can everyone else and have as much chance of meeting up, per the rules we've heard of in the HV. There are two issues here: one is that being "slightly away" in hyper effectively means "undetectable," so anyone can gather a fleet a light-minute outside of any target and be effectively undetected - though not zero. The other is that the ability to gather forces is chancy - for this, you have to travel in formation. That means a fleet could loiter waiting for the time to attack, but it can't be met by a DB coming from elsewhere with the orders to attack.

As often as an army catches a messenger trying to tiptoe through their camp in the dead of night. That is what this thread is about. It is a dead giveaway. No pun intended.

Bad analogy. Again: per the rules of the HV, no one is patrolling hyper and the random encounter chance is effectively nil. So unless the enemy knows to search for a DB coming and knows where to search for it, it won't find the DB.

It happened to the Havenites when they thought they were tiptoeing through Pavel Young’s camp. Only to find out the Mother of all Loose Warheads had replaced him and figured out there was a fleet waiting in hyper to attack.

In n-space, not hyper.

I havn't seen it stated, but I believe loitering in hyper also causes hyperlog issues - any little energy use causes unaccounted for discrepancies in hyper which build up over time, so usually a waiting fleet does so nearby in normal space, not hyper, so it has an exact position.

And remember, if the log is off and you try to exit hyper too close to a gravity well, it will be fatal.

ThinksMarkedly wrote:In hyperspace? This goes against what we're told by the author. The Junction is probably the single most travelled cubic light-minute in the entire Galaxy, and yet both commercial and military navigators were making mistakes all the time. If it were possible to "map the region" in hyper, that wouldn't be happening. We're told that the only way to navigate in hyper is using the hyperlog, which is effectively an inertial navigation system.

There's an apparent internal contradiction here: the hyperlog is so precise that most navigation arrives within a few light-seconds of any location they desire to arrive. And yet, hyperspace meet ups seems to be impossible. My guess at explaining this is that one doesn't design military operations that require meeting up in hyper, because the chance of hyperlog imprecision sending them just too far to meet is too high, something like 1 in 20.

As for meeting in n-space, we've discussed to exhaustion. Transiting six light-months out isn't "gathering in the MBS" but instead "gathering in interstellar space." And with no nearby "landmarks," I'm not sure how well you could orient yourself in case the hyperlog was imprecise.

Taking these in reverse order - for the MBS, specifically because it's a binary star system, you probably could ID both stars from 6 lightmonths out and their relative positions (compared to their recalculated ones) probably lets you orient yourself well enough; since even the worst miss on hyperspace exit isn't going to put you a LY out of position on the other side of the system. Also, I'm not actually sure that emerging another 5 light-months beyond where the Sharks super sneaky entrance was detected is actually far enough out to avoid detection from Manticore's massive system grav arrays.

As for the navigation - yeah that does seem a little odd. It's true that sensor range is sharply curtailed in hyper compared to normal space. So you need to hit the rendezvous closer to see the other fleet. But you'd think that the distance compression in hyper would mostly or entirely offset that -- especially if the rendezvous was set in the higher bands where the compression ratio is higher. (Meaning if your nav error was a horrendous light-hour in normal space, well the Theta band compression ratio is 3000x so you'd presumably only started with a nav error of 1.2 light-seconds up there that got magnified as you dropped through the intervening bands and out into normal space.
(But this is just another of the unresolved things about how hyper works)

OTOH I do agree with the preceeding post that hyper log errors should continue to accumulate the longer you're in hyper; so waiting around should make your position error larger and larger. (Both because the inertial navigation error in inherently cumulative; but also specifically without any outside reference point if you didn't manage to come to a full stop relative to the target system you'd slowly be driving without any acceleration and inertial reference units integrate position based on all the accelerations. So if it things you've stopped but you actually have a half kilometer/hour drift you don't have to wait around all that long before you're badly wrong about your location)

In any case we've never seen ships make a long range rendezvous in hyper; just the very short distance ones necessary to spring the Paul Revere style traps. (Traps which, themselves, don't appear to be set up very far in advance -- so the waiting fleet seems to have minimal waiting time)

Jonathan_S wrote:Taking these in reverse order - for the MBS, specifically because it's a binary star system, you probably could ID both stars from 6 lightmonths out and their relative positions (compared to their recalculated ones) probably lets you orient yourself well enough; since even the worst miss on hyperspace exit isn't going to put you a LY out of position on the other side of the system.

Hmm... can you triangulate? Comparing a star against the background stars should give you a direction vector. For any star whose luminosity you know precisely, you can tell from the apparent brightness how far away you are. The closer this is, the more precise the result is. This alone should give you a position vector. Then, for a binary system whose orbits you know, the separation between the two stars and the background stars would also tell you the distance (time is distance divided by the speed of light), improving your precision.

You can also use GPS (Galactic Positioning System) based on pulsars: knowing their spin-down times, you can tell from the pulse frequency how far away you are from each.

The question is how precise. I doubt you can get something in the order of thousands of km, though Wikipedia suggests ±5 km is possible. If you can't, that means the other force you're trying to meet must be doing the opposite of being stealthy: it must have a beacon "here we are."

Also, I'm not actually sure that emerging another 5 light-months beyond where the Sharks super sneaky entrance was detected is actually far enough out to avoid detection from Manticore's massive system grav arrays.

That's an unknown. I just guessed that 6x / half light-year was sufficient. TEiF does say that the scouting force led by Tremaine into Galton multiplied the distance by 4 - even though the text mistakes weeks for months.

In any case we've never seen ships make a long range rendezvous in hyper; just the very short distance ones necessary to spring the Paul Revere style traps. (Traps which, themselves, don't appear to be set up very far in advance -- so the waiting fleet seems to have minimal waiting time)

Don't forget that the two components of those forces would have travelled together. So the inertial navigation only needs to account for the time since the two separated in hyper, before one of them translated down. Then the Paul Revere destroyer only needs to reverse that portion.

ThinksMarkedly wrote:

Jonathan_S wrote:In any case we've never seen ships make a long range rendezvous in hyper; just the very short distance ones necessary to spring the Paul Revere style traps. (Traps which, themselves, don't appear to be set up very far in advance -- so the waiting fleet seems to have minimal waiting time)

Don't forget that the two components of those forces would have travelled together. So the inertial navigation only needs to account for the time since the two separated in hyper, before one of them translated down. Then the Paul Revere destroyer only needs to reverse that portion.

And much of the time we've seen a Paul Revere trap it was laid by the defenders. And those should have even less drift to worry about.

(Since entering hyper doesn't generate a normal space signal I'd assume that a defending Paul Revere force would position themselves in some out of the way bit of normal space well beyond the system's hyper limit, until an enemy actually did show up. Then they can silently slip into hyper and wait, likely for no more than a few hours, to be summoned).


I'm also now recalling that we've the RMN CLAC adopt a drop and hyper away tactic where they'll wait to be called back to recover their LACs. But I don't know if they wait the whole time in hyper or if they drop back down into some pre-planned normal space rendezvous spot. But even if they wait in hyper they don't stay away long enough for it to be hard for a destroyer to come find them; there's just not that much time for their hyper logs to drift.

ThinksMarkedly wrote:In hyperspace? This goes against what we're told by the author. The Junction is probably the single most travelled cubic light-minute in the entire Galaxy, and yet both commercial and military navigators were making mistakes all the time. If it were possible to "map the region" in hyper, that wouldn't be happening. We're told that the only way to navigate in hyper is using the hyperlog, which is effectively an inertial navigation system.

There's an apparent internal contradiction here: the hyperlog is so precise that most navigation arrives within a few light-seconds of any location they desire to arrive. And yet, hyperspace meet ups seems to be impossible. My guess at explaining this is that one doesn't design military operations that require meeting up in hyper, because the chance of hyperlog imprecision sending them just too far to meet is too high, something like 1 in 20.

As for meeting in n-space, we've discussed to exhaustion. Transiting six light-months out isn't "gathering in the MBS" but instead "gathering in interstellar space." And with no nearby "landmarks," I'm not sure how well you could orient yourself in case the hyperlog was imprecise.

Very interesting conversation.

Actually I don’t know how a ship finds its own ass from a hole in the ground, much less a waypoint. Especially with a very long trip of many light years. If the hyperlog is precise, then there should not be a problem. If the hyperlog is not precise then there should be a problem. Intuitively.

How does a ship account for the imprecision? On the one hand it all makes a little sense if you think about it. OTOH certain aspects of it does not make sense. If there is drift while waiting in hyper, it appears the drift cannot be too great if CLACs are ordered to fallback into hyper in the heat of battle waiting to be recalled. Even if the drift isn’t that great it should be bad enough that the CLAC cannot reappear in the battle at a bearing / location that is precise enough to be of tactical assistance. And the CLAC cannot transit down into n-space in the midst of battle if there is a chance it would be needed, because it takes too much tactical time to recharge the hyper generator. Therefore, a CLAC remains in hyper for at least 45 minutes. That time would have been much longer before MDMs when energy weapons win the battle. There were no CLACs before MDMs but there still would have been a need for even longer loiter times in hyper to execute a mouse trap in the age of battles that culminated with energy weapons.

First, let’s try to account for the imprecision of the hyperlogs.

The only way that I could ever make sense of it is to compare hyper space to a raging rapid and the fact that the mechanics of travel acts as it does in the age of sail. Mostly. Attempting to come to a complete stop in a wet navy by lowering the sails of a ship in a raging rapids is still going to result in ship movement unless the ship deploys some sort of an anchor. Sails cannot be lowered while in hyper. So it would seem that ships are like most real life sharks; they must keep moving or they will die.

Which brings me to my first question.

1. How does a ship drop anchor in hyperspace?

If I am not mistaken, wedges do not work in hyper. I suppose reaction thrusters could maintain station if there was some way to know how much thrust needs to be maintained to counteract movement relative to n-space; i.e., thrust / duration. If ships can wait in hyper for a short time then there does not seem to be a lot of drift. I would estimate loiter times in text to be equal to at least thirty to forty five minutes.

If we count the longest wait in hyper to spring a mouse trap it could be a few hours if we allow for the time it takes an enemy to cross the hyper limit after hypering in. Thirty to forty five minutes to a few hours is a significant amount of time for a fleet to loiter in hyper for a destroyer waiting to transit up to summon that fleet.

It is true that that amount of time pales in comparison to the wait times that would occur if a fleet tries to drop anchor for days or weeks waiting for orders to attack. But for short wait times the drift is allegedly manageable. Probably because, as you all say, a destroyer calculates the probable drift of the “currents.” The analogy in real life is determining the location of a body or object that has been dumped or dropped in the ocean by the ocean’s currents.

2. If the amount of drift can be calculated in the HV for short durations, then why can’t it be calculated for long durations?

I think the use of hyperlogs is precise if a warship follows the logs to the letter which implies that there must be a specific waypoint listed. For instance for the sake of argument, I don’t think the logs can say, “from the MBS to Gryphon via hyper is going to take 3 hrs." I would think it has to list a specific beginning waypoint inside or relative to the MBS. Navigation buoys?

The system is large. Is the beginning waypoint that is associated with the MBS in the middle of the system? My point is it would appear that long distance hyper travel should require a ship to drop out of hyper in the closest system to reset the hyperlogs. Like a bus trip that does not go straight through to your destination. It would seem that the longer the trip in hyper the more imprecise the logs would be. But that is not the case that we are presented with in the books. Trips are straight through, direct connections. So I think the problem in navigation is the laziness of the navigator and / or the impracticality of following the logs to the letter. Plus, travel along any route varies. During a track meet, each runner's position is staggered to account for the longer distance that must be run when entering turns. Curves. Is hyperspace a straight line between two waypoints? Ships don't travel the same lanes even on well traveled routes.

I can’t believe ships do not constantly drop out of hyper near a known system just to reset the hyperlogs. Annoying the heck out of systems like the MBS. “We’re just passing through!”

Therefore, how does a ship like a CLAC drop anchor to prevent drift? If there is SOME drift then it should be impractical for a CLAC to return to the battle in the correct tactical position. Mousetraps should be impossible. Refueling should be impossible, etc.

Unless there is a way to drop anchor. But wedges don’t work in hyper.

3. But what about a spider drive? Does a spider drive work in hyper? If it does, then a spider drive might be able to drop anchor and halt movement in relation to n-space. Can the tractors of an LD attach itself to the nearest wall as an anchor?



Note: The problem with drift should be greater in the highest bands.


.Apologies for the ninja poster that cannot wait until I conclude my post. What is the rush to post after over 24hrs since the last post. And one can see edits that are occuring because a post refreshes itself while anyone is looking at it. Yes, I have to do some edits while logged in. Your consistent ill manners are appalling.


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penny wrote:Unless there is a way to drop anchor. But wedges don’t work in hyper.

3. But what about a spider drive? Does a spider drive work in hyper? If it does, then a spider drive might be able to drop anchor and halt movement in relation to n-space. Can the tractors of an LD attach itself to the nearest wall as an anchor?

But Wedges (and spider drives) do work in hyperspace, unless the ship is in a gravity wave where sails MUST be used.

The suggestion is that a ship cannot drop anchor in hyperspace, as someone said they expect hyper-log errors to accumulate while sitting with the drive in neutral (the question about a spider drive grabbing the wall to stop movement is unanswered). However the drift is not so much that a fleet cannot be summoned from hyperspace in the maneuver used at Sidemore. The drift mainly shows up in long distance travel.

In the days when sailing ships had to use dead reckoning, they could still see the sun and stars on clear days to help correct positioning. In hyperspace, there are no good ways of marking location, except by dropping to normal space and checking the stars.

tlb wrote:

penny wrote:Unless there is a way to drop anchor. But wedges don’t work in hyper.

3. But what about a spider drive? Does a spider drive work in hyper? If it does, then a spider drive might be able to drop anchor and halt movement in relation to n-space. Can the tractors of an LD attach itself to the nearest wall as an anchor?

But Wedges (and spider drives) do work in hyperspace, unless the ship is in a gravity wave where sails MUST be used.

The suggestion is that a ship cannot drop anchor in hyperspace, as someone said they expect hyper-log errors to accumulate while sitting with the drive in neutral (the question about a spider drive grabbing the wall to stop movement is unanswered). However the drift is not so much that a fleet cannot be summoned from hyperspace in the maneuver used at Sidemore. The drift mainly shows up in long distance travel.

In the days when sailing ships had to use dead reckoning, they could still see the sun and stars on clear days to help correct positioning. In hyperspace, there are no good ways of marking location, except by dropping to normal space and checking the stars.

Then a ship's drive should be able to precisely counteract movement relative to n-space. That must be what wedges actually do, but just not efficiently enough. It could turn out to be that wedges are too powerful for precise station keeping in hyper. Whereas it could be that spider drives are more precise efficient at station keeping. They are less powerful, and they might be able to grab the wall to hold onto. Of course that would require the wall itself to be stationary.


P.S. You couldn't wait for me to complete the post? What was the rush? There had not been a post for over 24 hrs. And any poster can see edits occuring because the post refreshes. Why do you do that? After I have informed you of the problems I am having.

I'm done.

My apologies to the many fans who drove this thread to an average of over 250,000 views a month at one point.

Thank you.