The perplexity score increases as we increase the number of tokens.
Was thinking this is will be true. As the increase the sentence will not be meaningful.
Hi @Jing_bot
The quiz question is perplexing 
. What is being meant by:
The perplexity score increases as we increase the number of <UNK> tokens.
- Is it relative <UNK> count to other words?
- Is it absolute <UNK> count in a sentence?
Since the correct answer is “False” - meaning the above statement is incorrect, the only interpretation of it can be the former → “relative <UNK> count” - meaning the probability of the sentence gets higher when we reduce the uncertainty (the branching factor - fewer words in the dictionary).
This is in line with the course Video: Out of Vocabulary Words time 3:46.
On the other hand, if reading without context, and talking about arbitrary sentence perplexity, then it wouldn’t be clear - it could reduce, not change or increase the perplexity score of a given sentence.
Cheers
P.S. There’s an excellent blog post about perplexity and the way to understand it.
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