chromatic_step

std.linalg.chromatic_step · Level L3

Try one more colour: k ← k + 1 and run k_colorable. The body chromatic_number runs.

k ← k + 1; found ← k_colorable(A, k)

Signature

chromatic_step(k: f64[], found: f64[], col: f64[n], A: f64[n, n]) → f64[], f64[], f64[n]

Structure

The function as NOVA stores it: one box per input, operation and output, and arrows that carry values. A double border marks another library function this one runs — called once, or by Scan once per element; select it to open that function.

kf64[]1.0Af64[n, n]foundf64[]colf64[n]Addk2k_colorableok_kIdentityfound2Identitycol2k2f64[]found2f64[]col2f64[n]
  • input
  • operation
  • constant
  • call
  • output

Verification

  • Signature proven by NOVA’s shape solver, for every size.
  • Equal to the reference k + 1, k_colorable(A, k + 1) in exact rational arithmetic, on all 40 test cases.
  • All 206 float64 results are exact: the error is zero.
  • Interpreter and NumPy backend return bit-identical results.
  • At float32 too: the 40 test cases rounded to float32, and 40 of them exact, with zero error.
Accuracy in detail
correctly rounded (the float64 nearest the exact value)
100%
bit-equal to the NumPy formula in float64
100%
largest error, in units in the last place
0

Identity

sha256:4da49a7afb345752013c84d5d323db3f20ed8525444ea164944a7bd598fffde7

The semantic hash of the graph. It changes when the program changes, and never when only its documentation does.

Control handle

Symbol
Ω:std.linalg.chromatic_step · Ω:chromatic_step
Pins
sha256:d6f2b1b22a5d5a810cd0de977bdb5c571f6de78645b016735ea96a0c242975abthis graph and the 3 it reaches through calls
Evidence
sha256:15f7bb37080951554f06748c5f73d822893baf63d4ab77daf89438e8ac22e7b9the hash of its verification record
Needs
no capability: a pure function

Through NOVA’s control layer, the symbol launches this function only while the program still matches what it pins: a change to this graph, or to any graph it reaches, needs a migration first.

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