# Better Informatics

### DBS - Database Systems | drps, info, papers December exam Edit on GitHub

This course is being renamed to Introduction to Databases (IDB)

• Normal Form checker (both BCNF and 3NF)
• Revision notes by Ben Shaw
• Relational algebra calculator / engine, example schema definition for tutorial 1
• Exam tips:
• Don’t forget semicolons, they will knock marks off for this!
• They want to see efficient solutions!
• Derivation using the Armstrong’s axioms: all steps and axioms in your derivation should be clearly mentioned
• It’s also worth understanding that there could be multiple correct proofs for a given implication so detailed explanations would make it easier for marker
• Relational algebra questions: consider how your answer behaves when certain relations are empty (tutorial 1, question 3)
• Relational algebra FAQ:
• Operations only return unique tuples. That means if you project on a single column, each row will be unique. This is because (definition) “Relations (tables) are sets of records of the same length”
• easily consumable stuff by b0rk:
• SQL to XXX FAQ (for those with experience in SQL/NoSQL)
• Relational algebra:
• project (pi)
• select id, name, city from customers;
• RethinkDB (NoSQL) people will know this as .pluck
• select (sigma)
• select * from customers where name = 'Alice' or name = city
• RethinkDB (NoSQL) people will know this as .filter
• Unknowns / NULL
• Unknown is represented as NULL in SQL,
• unknown = unknown is really NULL = NULL,
• all comparisons where at least one of the arguments is NULL, evaluates to unknown (which, again, is NULL).

### IAML - Introductory Applied Machine Learning | drps, info, papers December exam Edit on GitHub

• See shared drive for some unofficial solutions.
• An amazing online course at Caltech by Yaser Abu-Mostafa - link
• A very detailed yet simple visual explanation of PCA, applied to a real-world scenario (on stats.stackexchange)
• Clearer (than our slides) explanation of SVMs
• Visual explanations of ML and Linear Algebra concepts
• Examinable topics summary - Having analysed IAML exam papers from 2012 to date, here is the summary of topic covered.
• To help with the understanding of topics that come across more often than others, score = frequency of occurance, expressed as % over 12

### SP - Speech Processing Edit on GitHub

Answers to multiple choice for past papers here.