heuristic-excess
At its defaults it draws two greedy contraction rules against the exhaustive optimum, over 60 random networks. Each curve is one rule's excess over the exhaustive answer, sorted, so the horizontal axis is the share of networks at or below that excess. Pairing whichever two operands are cheapest to multiply is optimal on 1.7 per cent of them, has a median excess of 1.446 and a worst case of 25.4. Pairing whichever two leave the smallest result — the rule the libraries ship — is optimal on 50.0 per cent with a median of 1.0026. The upper curve is the spread between each network's own best and worst orders, median 607, which is the size of the thing being searched for.
heuristic-excess is one function in lib/figures/contract.js —
contraction order — one expression, one value, and orders that differ by two million. Everything below came out of it during this build, at
arguments taken from the essays rather than invented for this page. A figure here is the
figure a reader meets in an essay, and if the generator changes, this page changes with it.
At its defaults
Drawn even though every essay passes arguments — which on this site is every essay, at 100% of placements since the standard pass. A default nothing exercises is a trap for the next essay to call this with none, and this is the page where a default that has drifted from the figures around it becomes visible.
Each curve is one rule's excess over the exhaustive answer, sorted, so the horizontal axis is the share of networks at or below that excess. Pairing whichever two operands are cheapest to multiply is optimal on 1.7 per cent of them, has a median excess of 1.446 and a worst case of 25.4. Pairing whichever two leave the smallest result — the rule the libraries ship — is optimal on 50.0 per cent with a median of 1.0026. The upper curve is the spread between each network's own best and worst orders, median 607, which is the size of the thing being searched for.
trials: 60
The arguments are the ones Sketching what is never unfolded passes. A value drawn at the generator's defaults instead would be a picture no essay asked for and no assertion has been run against.
Each curve is one rule's excess over the exhaustive answer, sorted, so the horizontal axis is the share of networks at or below that excess. Pairing whichever two operands are cheapest to multiply is optimal on 1.7 per cent of them, has a median excess of 1.446 and a worst case of 25.4. Pairing whichever two leave the smallest result — the rule the libraries ship — is optimal on 50.0 per cent with a median of 1.0026. The upper curve is the spread between each network's own best and worst orders, median 607, which is the size of the thing being searched for.
trials: 120
The arguments are the ones The order the products are taken in passes. A value drawn at the generator's defaults instead would be a picture no essay asked for and no assertion has been run against.
Each curve is one rule's excess over the exhaustive answer, sorted, so the horizontal axis is the share of networks at or below that excess. Pairing whichever two operands are cheapest to multiply is optimal on 3.3 per cent of them, has a median excess of 1.471 and a worst case of 25.4. Pairing whichever two leave the smallest result — the rule the libraries ship — is optimal on 53.3 per cent with a median of 1.0000. The upper curve is the spread between each network's own best and worst orders, median 558.9, which is the size of the thing being searched for.
trials: 40
The arguments are the ones The order the products are taken in passes. A value drawn at the generator's defaults instead would be a picture no essay asked for and no assertion has been run against.
Each curve is one rule's excess over the exhaustive answer, sorted, so the horizontal axis is the share of networks at or below that excess. Pairing whichever two operands are cheapest to multiply is optimal on 0.0 per cent of them, has a median excess of 1.337 and a worst case of 25.4. Pairing whichever two leave the smallest result — the rule the libraries ship — is optimal on 42.5 per cent with a median of 1.0140. The upper curve is the spread between each network's own best and worst orders, median 639.8, which is the size of the thing being searched for.
trials: 20
The arguments are the ones The order the products are taken in passes. A value drawn at the generator's defaults instead would be a picture no essay asked for and no assertion has been run against.
Each curve is one rule's excess over the exhaustive answer, sorted, so the horizontal axis is the share of networks at or below that excess. Pairing whichever two operands are cheapest to multiply is optimal on 0.0 per cent of them, has a median excess of 1.296 and a worst case of 7.53. Pairing whichever two leave the smallest result — the rule the libraries ship — is optimal on 50.0 per cent with a median of 1.0034. The upper curve is the spread between each network's own best and worst orders, median 810.1, which is the size of the thing being searched for.
trials: 90
The arguments are the ones The order the products are taken in passes. A value drawn at the generator's defaults instead would be a picture no essay asked for and no assertion has been run against.
Each curve is one rule's excess over the exhaustive answer, sorted, so the horizontal axis is the share of networks at or below that excess. Pairing whichever two operands are cheapest to multiply is optimal on 1.1 per cent of them, has a median excess of 1.443 and a worst case of 25.4. Pairing whichever two leave the smallest result — the rule the libraries ship — is optimal on 50.0 per cent with a median of 1.0026. The upper curve is the spread between each network's own best and worst orders, median 538.6, which is the size of the thing being searched for.
What it checked while drawing
Every figure above asserted its own claims on the way to being drawn, and a claim that failed
would have failed the build rather than drawn a wrong picture. Those assertions used to leave
no trace at all: a passing one returned true and the only evidence the figure had
checked anything was that nothing crashed. The list below is what they actually said, collected
by running this generator with an observer installed — not a description of
what it is believed to check.
3 distinct claims across 6 sets of arguments, grouped below by shape — because most of them are one sentence with a different number in it, and how many separate times that sentence was put to the test is the informative part.
a number of networks to price
and pairing by smallest result is the better of the two
no heuristic beats the exhaustive order
Against the rule
The rule does not apply to it. It factorises nothing, so there is no residual it could be withholding. That is worth stating rather than leaving blank: a site that reported the rule as satisfied by every generator would be counting mostly generators the rule never reached.
Across the library: the rule bites on 146
of 287 generators —
131 print a residual and
15 are exempt with a published reason;
141 factorise nothing.
Read from lib/residual-rule.js, which is the same body the gate enforces from,
and the gate's last check fails the build if this page and it disagree about any generator.
Where it is called
Changing this generator changes every figure on this list. That is what makes the list worth publishing rather than keeping in a check script.
Sketching what is never unfolded
A range finder multiplies its matrix by a few random vectors. For a mode-k unfolding those vectors have n^{d−1} entries, so the random object is the size of the tensor divided by n — and by six indices it is larger than the tensor it is sketching.
Sparsity, and what elimination costsThe order decides the memory
Four elimination orderings on one matrix give factors of 1,739, 1,354, 1,413 and 1,026 entries. All four factorisations are exact, all four return the same answer, and the one with the better asymptotics is not the one that wins.
Where the flop count stopped predicting the timeThe order the products are taken in
The sparsity field's first essay says the elimination order decides the memory. This is the same sentence about arithmetic: a contraction of several tensors over shared indices has one value and many evaluation orders, and on the inner product of two trains they differ by a factor of two million.
Where the flop count stopped predicting the timeThe same arithmetic at a different price
A blocked and an unblocked elimination perform 72,568 operations each — the same operations, associated differently — choose the same pivots, and return a factorisation identical to the last bit: ‖PA − LU‖/‖A‖ = 4.487946226420872·10⁻¹⁶ in both. One of them moves 41,332 words between fast and slow memory and the other moves 19,476.