I assume nothing. There is canon evidence for the existence of a Second, Third, Fifth, Sixth, Seventh, Ninth and Tenth fleet. These fleets are numbered sequentially with no outliers; there is no reason for a First, Fourth or Eighth fleet not to exist.
You are obviously assuming such, as you just admitted that there is no evidence of a First fourth and eight fleet existing. Using your logic, why does the US fleet not have a first fleet despite having second-seventh?
Just to belabour the point, I will list you the current divisions of the US army.
1st,
1st,
1st(thats right there are three!), 2nd, 3rd, 4th, 10th, 25th, 82nd, 101st. Accoding to you there are apparently 90 other divisions that must be somewhere, care to tell us?
Even so, that is still seven fleets, showing that parts of three of them cannot possible comprise a majority, let alone the total, of Starfleet vessels.
It tells us no such thing. Let me let you in on a secret, US Navy fleets have no organic vessels. Thats right, the numbered fleets do not own a single ship. All vessels are owned by the Atlantic and Pacific fleets. The numbered fleets are in charge of geographic areas and are only in control of vessels that are transiting through their area or operating in their area. That means that 5th fleet, in charge of the Persion Gulf, most of the Indian Ocean, and Red Sea has all kinds of ships because of the current conflicts (they have the same geographic mandate as CENTCOM). 4th fleet, however, in charge of South America, goes through most of the year with one or two ships if any. Just to belabor the point, 2nd and 3rd fleet control the Atlantic and Pacific coasts respectively and are only used for training (we don't do many operations in those peaceful waters). Vessles in port belong to no numbered fleet whasoever.
Again, you are assuming that just because an organizational division is called a "fleet" it is in pocession of an actual fleet of vessels. Furthermore, you are assuming that whatever number of vessels each one has they are all a significant concetration. There is nothing to attest to this.
You are correct. There are, however, instances where fleet sizes are directly stated. The Operation return fleet consisted of 600 ships; even if we ignore the fact that it was incomplete this means three fleets can comprise 600 vessels, or 200 per fleet. The Seventh consisted of 112 ships during one operation.
1.) Sisko's fleet was not a numbered fleet, so its size is irrelevant to determining normal numbered fleet operating numbers. It was a special concentration created for a specific purpose (as most battle fleets are in the real world).
2.) You are assuming that his fleet was made up of only vessels from the three fleets mentioned (as well as all of those three fleets mentioned). There is no reason for this.
3.) I really doesn't matter what size a fleet is at any one time. As I stated there is nothing that limits any fleet to any particular number of vessels. It could vary form ten ships to a few hundred all depending on the course of the war and the importance of that fleets stationing.
In short the only thing we have that speaks to the number of vessels in starfleet is the number 600 (not telling us the tonnage of any of those combatants) and what we have seen on screen.
The numbered fleets in DS9 have always, always been mentioned in the context of being active combat fleets that persisted throughout the war. Whatever a modern day fleet may be, in DS9 they are considered to be large-size, independent combat forces with a roughly fixed size.
The bolded part is nice, but irrelevant. Just because a fleet was active at one point in the war doesn't mean it was at another and thus is subject to rather severe shifts in the number of units assigned.
As far as them being considered large sized, independant, solely combat oriented or fixed in size, you just made that up. The whole problem is that we have never been given an order of battle or anything alse to make a qualitative judgement of what Federation fleet typically consists of let alone consists of at any given time.
Well you mentioned on instance of a numbered fleet specifically described as a hundred odd vessels, coming back from a pitched battle no less. That doesn't speak well to your theory.
Even skeleton defences are still defences, unlike you stated in your earlier claim that the task force in SoA was all Starfleet had to offer. Even a handful of ships per core world amounts to a fleet bigger than the SoA one.
I said no such thing, I said "for all intents and purposes." If you have 70% of starfleet concentrated at a single system the remander, spread out throughtout the entirety of Federation territory under threat, that remainder is an irrelvance.
You are again making things up. First of all defenses do not automatically equal ships (let alone capital ships). Second of all not all ships are created equal. They very well may have stripped the rest of the fleets of their capital vessels, leaving destroyers/corvets/patrol craft to show the flag elsewhere. That means that while the uninvolved fleets might may have a number of vessles, the tonnage is not there. Thirdy, you are again pretending they said core worlds when what they said was Earth solely.
Incidently you are also assuming "core worlds" means dozens of planets. It could be just a hand full and not nessecarily all requiring a defense (some are going to be further from the front than others). It is irrelevant though, nobody says "core worlds."
The timespan between Sisko getting the green light for his plan and the launch of the task force is precisely half an episode - the middle bit of Favor The Bold. The occupation too six episodes, the counterattack sure didn't.
And they give the timeframe when? So now your position is so enlarged that you think Starfleet has 600 close enough to concentrate within a few hours?