The goal is to ensure quality for a period of time after you buy it. That can be several days to several weeks, depending on the item. For instance, milk, assuming proper refrigeration, should last five to seven days past its sell-by date before turning sour.
An autoencoder is a neural network that is trained in an unsupervised fashion. The goal of an autoencoder is to find a more compact representation of the data by learning an encoder, which transforms the data to their corresponding compact representation, and a decoder, which reconstructs the original data.
An auto-antonym (sometimes spelled autantonym), or contronym (also spelled contranym), is a word with multiple meanings, one of which is defined as the reverse of one of its other meanings. This phenomenon is called enantiosemy, enantionymy or antilogy. An auto-antonym is alternatively called an antagonym, Janus word (after the Roman god), enantiodrome, self-antonym, antilogy, or addad (Arabic, singular didd).