A three-instruction leap-year test hides the constants 1073750999, 3221352463, and 126976. I rebuilt an 18-bit version with Z3, then traced how the multiply, mask, and threshold encode divisibility by 4, 100, and 400.
Benchmarked on an M4 Mac mini: Ben Joffe's 2-instruction weekday hack beats plain %7 by 1.6-6.4x in clang, Rust, and V8, loses 3x in CPython. Plus a 25x V8 -0 deopt trap.
Verified in SymPy: the 3-variable map from Alpöge's post has constant Jacobian determinant −2 yet sends three points to (−1/4, 0, 0). What changes for n ≥ 3 and what stays open.
How much does periodic password rotation or character-class enforcement actually help? A look at the numbers: leak probability, entropy, and user behavior.
A paper claims that a single binary operator eml(x, y) = exp(x) - ln(y) combined with the constant 1 can express all elementary functions — arithmetic, trig, logarithms, even pi. I read the paper and tested it in 5 languages.
