a symbol is an agreed,
distinguishable state.
distinguishable state.
distinguishable: the receiver can tell it apart from the others.
agreed: both sides gave it the same meaning, beforehand.
what makes light mean something?
image: ai-generated (gpt-image-2)
perfect reception, perfect nonsense
every colour arrived correctly. the message did not.
the agreement, written down
ALPHABET = {
"red": "00",
"green": "01",
"blue": "10",
"yellow": "11",
}
both sides need this table. it is not data, it is a promise.
the guessing game, measured
five questions. every time.
not every answer is worth one bit
you cannot choose which answer you get.
what a question is worth on average
and in general
a fair split is the only way to get a whole bit.
one bit
a light switch holds one. no computer required.
try it: which question is worth more?
what a bigger alphabet buys
same file, same symbol rate. only the alphabet changed.
two symbols are enough for anything
what a big alphabet does per symbol, two symbols do in a group.
when symbols are not equally likely
rare symbols may cost more. common ones must not.
the catch
the size of your alphabet is not a matter of taste. it is a measurement.
in the workshop
agree on your alphabet and write it down
measure a profile for every symbol
fill send_symbol() and receive_symbol()
run a whole word and count the errors
light means nothing
until you agree what it means.
until you agree what it means.
and how much it means, you can count.