# 2018w3

Created: Sun 2018-01-14

### fri jan 19

• Read introduction of Deep Learning (Goodfellow et al). The principle of deep learning has been around for decades. The introduction gave an outline of three waves of deep learning. The latest wave of deep learning is made possible by large data sets and cheap computing power.
• This book uses three chapters to outline necessary math background. Linear algebra, probability and numerical computation. Each of them very difficult to understand in itself.
• This deep learning textbook is not technically part of the curriculum. I just find it useful to read.

### thu jan 18

• Didn't learn much.

### wed jan 17

• Listened to a lecture about search and complexity. To illustrate why efficient algorithms are important, S asked us to guess a number in pairs. (Then next thing you know: Binary search.)
• Exposed to the notion of Ordo, or big-O. Somewhat confused by this concept. But the fact that algorithms perform differently depending on the amount of input data was a new discovery to me.
• How hash table works is bewildering. And it seems messy to me. The data structure “dictionary” in Python is a hash table. The word hash may well mean “messy.” (It is indeed the case.)
• Since a hash table is messy, “load factor” (λ) becomes relevant. The higher the number of keys in a hash table, the more likely “collision” happens. Which will slow down access. A λ of 0.75 is usually good.
• In the implementation of Python dictionaries, size of hash table – (what else could “size” in today's slides mean?) – automatically increases when the λ gets larger than \frac{2}{3}. (“Increase” happens with a “rehashing”. Which is said to be “expensive”.)
• For the syntax course, listened to the CKY föreläsning (aka CYK). I really need to spend more time on this.

### tue jan 16

• Began taking the couse of syntactic parsing. Will need to read Jurafsky very carefully. And also the DP book.

### mon jan 15

• Began learning how to implement graphs with Python. Did some exercises.
• Submitted a mockup survey.
• Will skip the course on Thursday, because will not be eligible to do it anyway.

### sun jan 14

• continue working on assignment resubmissions.
• in the end, handed in the second part of assignment 4. This took longer than I planned. Ideally, ass 4 would have been finished yesterday, and today I can finish another resubmission.

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