Roomba, Cat, Human: A comparative analysis of my apartment's economy

	Roomba	Cat	Human
Effect on floor	Cleans floor.	Makes floor dirtier: cat hair, litter particles, etc.	Makes floor dirtier: hair, skin particles, food crumbs, etc.
Food	Feeds self: docks at charging unit when it is low on energy.	Cannot feed self: dependent on human to manage food intake, or else he gets incredibly fat.	Feeds self: from takeout, grocery store, or free food at work.
Hygiene	Cannot clean self: dependent on human to clean brushes.	Cleans self: with tongue.	Cleans self: with fixtures in bathroom.
Waste	Cannot eliminate own waste: dependent on human to empty dust compartments.	Eliminates own waste: in litterbox.	Eliminates own waste: in toilet.
Money	Cannot pay for self: dependent on human to pay for electricity.	Cannot pay for self: dependent on human to pay for food, litter, etc.	Pays for self: supports apartment economy through cash inflows from outside job.

Conclusions:

• If Roomba could clean itself and eliminate its own waste, it would be strictly more functional than Cat.
• If Cat could regulate its own food intake and get a job, it would be functionally equivalent to Human.
• Relationship between Roomba and Human is clearly mutualistic. By contrast, relationship between Cat and Human appears to be strictly parasitic, or else involve some exchange that is not captured by this analysis.