The tile system a machine is drawn as, and its grid #
The instance the hardness reduction emits, read semantically: a
FirstOrder.Language.wtile-structure on the tagged triples
DescriptiveComplexity.TilePt, with the tiles of
DescriptiveComplexity.Problems.Wide.TilingHard.Tiles and an order whose
digits come last.
That last point is what makes the grid the right size. A coordinate of
DescriptiveComplexity.WideTiling is an address holding digits alone, so the
square is indexed by the subsets of the diagonal – one per subset of the
machine's own instance, which is exactly one per tape address and one per time
step. The other points of the emitted universe are tiles, and they are ordered
below every digit, so they never enter a coordinate and never disturb the
binary-number order the coordinates are compared by: two coordinates differ at a
digit, and there the emitted order is the machine's own.
The order on the emitted universe #
A linear order on the tags, to order the points that are not digits.
Dependency graph
The order the emitted instance carries: the points that are not digits first, in the lexicographic order of their tag and their triple, then the digits in the machine's own order.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Dependency graph
The lexicographic order on the emitted universe is linear – Mathlib's,
read through DescriptiveComplexity.tagTupleLe_iff_le.
Dependency graph
A digit is determined by the element it is the digit of.
Dependency graph
The emitted order is linear, given that the machine's is: the digits carry the machine's order, and everything else the lexicographic one.
Dependency graph
Between two digits the emitted order is the machine's.
Dependency graph
The structure the reduction emits #
The tile system a wide machine is drawn as: the tiles of
DescriptiveComplexity.Problems.Wide.TilingHard.Tiles on the tagged triples,
with the digits last in the order. This is the instance the hardness reductions
emit, read semantically – the formulas that write it down come later, and are
checked against exactly this.
The bottom row is a parameter, because it is the one thing the two machines this drawing serves describe differently: the clocked machine's tape is a register file and the space-bounded machine's the ruler of all the segments. Everything else – the tiles, the two compatibilities, the edges and the corner – is the same drawing.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Dependency graph
The drawing of the clocked machine: the tile system above with the register file for its bottom row.
Equations
Instances For
Dependency graph
The drawing of the space-bounded machine: the same tile system with the ruler of all the segments for its bottom row.