Gerald Jay Sussman on biology & computation.
- The human genome is 1 GB. So is Windows OS.
- We have no idea how to program a 10¹²-unit thing like a human, or a cow.
- A salamander regrows three elbows if you break off its arm and reattach it — responding to local errors.
- We have no idea how to write computer vision in a few steps like neurons do.
- Program efficiency doesn’t matter.
- Memory is free right now.
- Computation is free right now.
- For a million bucks you can get a seriously computer—but what to do with it?
- Most of the cost of a computer program is paying programmers. —Huw Evans
- Yet we spend so much time modifying existing code. —Huw Evans
- Correctness doesn’t matter. (Getting a reasonable answer is fine.)
- Security doesn’t matter. (Humans are attacked by parasites all the time.)
- Biological systems are written to solve problems that the designer didn’t foresee.
- This LISPian stuff of writing programs that write programs looks very awesome; what I’ve pretty much always wanted to do with computers. (I tried and failed to use PHP’s multiple dollar signs to helpful effect.)
- Some stiff-matrix stuff that you can understand if you watch some Gilbert Strang videos.
- The point being: with bindings and such you can write a program that’s somewhat robust: performing operator overloading or similar things so that you can just tell the computer basically what you mean. (Rather than having to be so specific.)
- “Mathematical symbols are impressionistic” — just think about how the fnof; symbol is used — yeah, some function, whatever, ya know what I mean.
- Systems that accept a wide variety of inputs and only give a small range of outputs.
- Your cells have about 1 GB of ROM and a few megabytes of RAM.
- “Galileo discovered the value of a lie — to figure it out without the friction and then put it back in.”
- Propagators: Independent Stateless machines connecting stateful cells
- Satisficing / monotonically increasing local information about a referent.
- Synchronising problems in parallel computation go away.
- EE, not CS, point of view. (and I daydreamed off into economic theories using this circuit-diagram thinking)
- “I hate modern languages, even the ones I invent! … There are no names for intermediate parts [of expressions].”
- Min 44. Maybe this is an insight into explaining statistics to programmers. Errorful processes go in; this would be like multiple inputs (maybe a distribution assumption, maybe a bound on the error, maybe an independence assumption or equal variances) — and an errorful result comes out. Just like division-of-integers has two outputs—quotient and remainder—so do statistical processes spit out a ton of outputs as well:—answer(s) like beta;’s, error estimates (p’s and t’s), and tons of different ways of looking at what might be wrong with the assumptions (Durbin-Watson, structural F statistic, White estimators). Of course you could turn these outputs into Boolean by saying like “alpha; <.05 goes to TRUE” — but really the continuous alpha score is better.
- Expert reasoning in circuit diagrams as local reasoning between neighbouring pieces of the circuit diagram.
- Improving measurements by making independent measurements of the same thing by different methods.
- Tracking of provenance & shadow premises—….daydreaming: relationship to religious faith/scepticism.
- Giggling when logic subsystems conflict.
- Truth Maintenance Systems — the ability to back out
- Finding lies — medical statistical results
- Globally inconsistent worldviews that are locally consistent.
- Aaaand, find me the consistent sub-worldviews that are consistent.
“When a user is calling in need of help, don’t forget that he is a weakling. Only a loser would need to come groveling to you, begging for crumbs of help that may fall from your godlike lips. And he KNOWS that he is a loser in the race of the weak and the strong, that his kind is doomed to extinction. Therefore, show him no mercy. Treat him with the utter contempt that he deserves. It is the law of nature that you should do so.
Key Phrases:
“You aren’t very smart, are you?”
“I can’t believe you call yourself a programmer!”
“Our product is obviously too complex and advanced for you. Please desist from using it - you are soiling it.” “
Pardon, I keep finding better explanations or different ways to say the same thing.
this is most likely the last ARM presentation posting. This contains a good explanation of rotating variables.
A description of condition flags in ARM processing.
“N: Negative
The N flag is set by an instruction if the result is negative. In practice, N is set to the two’s complement sign bit of the result (bit 31).
Z: Zero
The Z flag is set if the result of the flag-setting instruction is zero.
C: Carry (or Unsigned Overflow)
The C flag is set if the result of an unsigned operation overflows the 32-bit result register. This bit can be used to implement 64-bit unsigned arithmetic, for example.
V: (Signed) Overflow
The V flag works the same as the C flag, but for signed operations. For example, 0x7fffffff is the largest positive two’s complement integer that can be represented in 32 bits, so 0x7fffffff + 0x7fffffff triggers a signed overflow, but not an unsigned overflow (or carry): the result, 0xfffffffe, is correct if interpreted as an unsigned quantity, but represents a negative value (-2) if interpreted as a signed quantity. “
