Question

Byte pair encoding is a data encoding technique. The encoding algorithm looks for pairs of characters that appear in the string more than once and replaces each instance of that pair with a corresponding character that does not appear in the string. The algorithm saves a list containing the mapping of character pairs to their corresponding replacement characters.
For example, the string "THIS_IS_THE_BEST_WISH" can be encoded as "%#_#_%E_BEST_W#H" by replacing all instances of "TH" with "%" and replacing all instances of "IS" with "#".
Which of the following statements about byte pair encoding is true?
A. Byte pair encoding is an example of a lossy transformation because it discards some of the data in the original string.
B. Byte pair encoding is an example of a lossy transformation because some pairs of characters are replaced by a single character.
C. Byte pair encoding is an example of a lossless transformation because an encoded string can be restored to its original version.
D. Byte pair encoding is an example of a lossless transformation because it can be used to transmit messages securely.

Answer 1

Answer:

C. Byte pair encoding is an example of a lossless transformation because an encoded string can be restored to its original version.

Explanation:

Byte pair encoding is a form of encoding in which the most common pairs of consecutive bytes of data are replaced by a single byte which does not occur within the set of data.

For example, if we has a string ZZaaAb, it can be encoded if the pairs of string ZZ are replaced by X and the second pair by Y. So, our data now becomes XYAb.

To get our original data, that is decode it, we just replace the data with the keys X = ZZ and Y = aa thus allowing our original data to be restored.

Since our original string is restored without loss of data, it implies that byte pair encoding is an example of a lossless transformation because an encoded string can be restored to its original version.