Can an unfinished product be patented? Say two companies are working on some software that does essentially the same thing: Can one of the companies patent the idea before it's finished to prevent the other company from working on it, or can they only patent the software once they have a working product?
Patenting does not require a working product in fields where the performance is predictable before hand. Chemistry and biology do have criteria regarding real results. The description in the patent application needs to be detailed enough that someone of ordinary skill in the field could make and use the invention. After company A gets a patent (might be 3 years or never), it can try to stop company B from making, selling, offering to sell, using, or importing whatever is claimed in the issued patent. You say "does essentially the same thing". If you accomplish the identical goal (speaker identification from noisy audio, for example) but accomplish it by following very different steps, then there may be no infringement at all.
You don't say what jurisdiction's patent laws you're interested in, and priority dates can differ in different schemes. I'm answering as to U.S. law only. In the United States, under the current hybrid "first-inventor-to-file" system, the priority date--the date that determines who "wins" if there are multiple claims to a specific invention--is, with some exceptions that I won't go into, the date of your first application. In other words, the date that the PTO got it in the mail. Once your application is submitted, it is--again, with some limitations I won't get into--prior art for the purposes of any later-submitted application. They can't get another application later, grant it first, and then deny your application based on the later-submitted application. Your application date would still win out. Could someone in the USPTO slip your application out of the stack, fudge the dates, and convince some other company to submit a similar application to get priority over you? Not as a practical matter, no. The USPTO isn't one guy in a room; it's a large organization, and the person who opens the mail, types in your application details, and sends you a receipt, isn't the same guy who knows whether your invention is any good or not. And, frankly, very few patentable inventions are going to be worth someone risking their job and/or jail time over--especially when there would be significant evidence of the misconduct--for example, your patent agent's files. So what are the chances that the examiner on your patent: 1) Is a nefarious character who has lived a life of public service long enough and wants to go rogue; 2) Has a friend in the mailroom who is also an expert in the field of your invention; and 3) Has a conduct in industry who is willing to break the law for the rights to your invention? Slim to none. And if you have an invention that is really so revolutionary that it's going to be worth so many people risking so much to steal it, odds are there will be other evidence that you were the inventor.
This sounds completely incorrect to me. First, subsequent research is not normally a "derivative work" for the purpose of copyright, since copyright doesn't protect your ideas but only the particular form in which you have expressed those ideas. Second, as the owner of the copyright, you can permit anyone to make any sort of copy or derivative work, or sell, assign, or license the ability to do so to other parties, without regard to whether the work has been published. The real reason that nonpublication of your work would stifle further research is that researchers will not have access to it.
Registered Trade Marks aren't the only form of trade mark protection. You also have the law of unregistered trade marks. Basically (and this is an over-simplification), it works like this: a business starts using a trade mark for a specified product: beard comb. Let's say that they don't even register a trade mark. they start selling load and loads (thinks 100s of thousands of $ or £ worth) they become well-known in that market segment. They accrue "goodwill" in the (unregistered) trade mark. That trade mark is protectable in law. That's a summary of the law of passing off aka the law of unregistered trade marks. So, if the new manufacturer is still manufacturing them in the country that you want to sell them in, you'll probably have a problem. This assumes that that country has an equivalent of the law of passing off. The tip then has to be - check to see if the manufacturer is still selling them. If you think it's a good business opportunity and worth a small amount of risk capital - a few hundred $ or £, file the trade mark application is see if anyone does anything about it. You can always withdraw it and avoid a dispute. You might also do a search for registered design rights. They protect the shape of the products (not what it's called - which is what a trade mark does).
You need to check if the original game developers patented the mechanics/rules of the game. For your example, Monopoly was patented, but expired in the 50s and while it would not be a copyright violation to mimic the rules/mechanics, it would be a different intellectual property violation (patent infringement). Spry Fox vs LOLAPPS is also relevant as it extends copyright protection to the implementation of an idea, but ideas (like rules/mechanics) cannot, by themselves, be copyrighted. This means that there is an avenue for the original developer/company to sue even if the visual/audible aspects are different, but the overall gameplay is the same. Also see Tetris Holding LLC vs Xio Interactive Inc. as it relates to the visual aspect of the game.
It is certainly possible to incorporate companies with the same name in two different states. If neither company does business in the other person's state under that name, it isn't actionable for either company. If one company was already doing business under its name in a state where another company is formed under that name, it would usually be possible to force the new company to cease and desist from using that name, either with an action directed at the infringer and the Secretary of State (or other official charged with business incorporations in a state) of that state, or in an action directly against the infringer alone. Also, even if a trademark isn't formally registered, it can arise at common law simply through use of a name in a particular market in a particular place. This is harder to prove and the remedies for violating a common law trademark a more limited, but it is not entirely unenforceable.
From what I can see on the USPTO registry, &quot;tweet&quot; is still not trademarked for the purposes you're talking about. Twitter has been working to secure that trademark, but I can't find any record of them having actually secured it. Just the same, I'd predict that using it will get you at least a cease-and-desist letter, and possibly a lawsuit. Whether you'd win that case seems to be a very open question, but that presumes you have the resources to litigate.
There are several issues - one is that patents are given for specific ways of solving a problem, sometimes very narrowly different from other ways of solving a problem, not for a result. There are usually many ways to achieve a result. Another, that you bring up, is “field of use”. That comes into play in method claims but not usually in device or systems claims. A claim to a “thing”- system, device, machine etc. is infringed by another thing (that fits within the claimed definition) just sitting on a shelf in a box. Intended use is not traditionally relevant. If a device for any intended use fits the words of a claim, it infringes. In your case the preamble of a system claim says “system for mixing or compositing in real-time, computer generated 3D objects”. At least in the US that would not usually be limiting to that use but just taken as a description of the thing, not requiring actual specified use to infringe. Read it as “capable of being used for”. Method claims can limit field of use. A method for getting rust cleared from a screwdriver that had a step “provide a rusty screwdriver” would be limited to that use. Another example would be a back scratcher configured exactly as a small garden rake but claimed in a method for scratching one’s back. Assume the garden rake is known - the backscratcher as a thing could not be patented, but a method of using something of a certain shape and design (small garden rake) to scratch your back could be. Someone with a garden rake couldn’t scratch their back even though they owned the garden rake. Note that a small garden sold as good for use as a backscratcher would be committing contributory infringement unless they had a license. Something being covered by a patent owned by its manufacturer does not mean it, or its use, does not infringe some other patent owned by a totally unrelated entity. Of course it is possible a manufacturer has licensed relevant patents of others. The patent you link to is not only described as used for broadcast. Gaming and other entertainment uses are mentioned. As mentioned in another answer, the Intel device works in a way that doesn’t fall under the claims of the sited patent. It has two cameras in total while the claims require a main camera and two additional cameras to do the position determination another with other inertial sensors. Some uses of the Intel device could theoretically infringe method claims in one or more un-sighted, unknown, patents. If someone bolted the intel device to a “film camera” and used the combination as described in the method claim you might get the quality image you need and only use the intel device for the position information. Then you might infringe.