Q.E.D. Code Podcast
1) QED 19: Dependency Tracking
The number of degrees of freedom in a system is equal to its number of unknowns minus its number of equations. That is also equal to the number of independent variables in the system. Dependent variab...Show More
2) Q.E.D. 18: Paxos
Leslie Lamport wrote a paper describing the Paxos algorithm in plain English. This is an algorithm that guarantees that a distributed system reaches consensus on the value of an attribute. Lamport cla...Show More
3) QED 17: Pythagoras
The Pythagoreans were a cult of Greek mathematicians that believed that all things were composed of large enough integers. Their leader, Pythagoras, is best known for the proof that the square of the ...Show More
4) QED 16: Elements
Euclid's Elements takes a disciplined, formal approach to proving assertions based only on simple axiomatic statements. While most of these axioms are elegant, one of them is more complex and wordy. I...Show More
5) QED 15: The Y Combinator
The Lambda Calculus uses simple replacement to compute expressions. However, it does not define a way to replace a parameter of a function with the function itself. That would seem to make it impossib...Show More
6) QED 14: Equivocation
Claude Shannon followed up one incredibly important paper with a second of even greater significance. In Communication Theory of Secrecy Systems, he analyzes cryptosystems based on the probabilities o...Show More
7) QED 13: The First Program
in a translation of a paper on the Analytical Engine, Ada Lovelace improved upon L. F. Menambrea's work by applying rigor to the calculations that he performed. But then she took things one iteration ...Show More
8) QED 12: Difference Engine
The Difference Engine was a mechanical computer that could calculate tables of numbers based on polynomials. The聽amazing thing is, though, that it could only add. How then could it accomplish this fea...Show More
9) QED 11: The Lambda Calculus
Alonzo Church invented The Lambda Calculus as a simple set of rules that, when applied correctly, could compute anything that you could do with a pencil and paper. But all it is is simple replacement....Show More
10) QED 10: The Two Generals Problem
Listener聽Richard Allen writes to ask about proving enough of a program correct to constrain the number of tests that must be written. I respond that you need both tests and proof.聽Otherwise, how could...Show More