polytope
polytope is one function. Everything below came out of it during this
build, at parameters taken from the essays rather than invented for this page — so a figure
here is the same figure a reader meets in an essay, and if the generator changes, this page
changes with it.
At its defaults
show: "dual"
show: "primal"
show: "slack"
show: "shadow"
What it checks while it draws
Collected by running the family and recording what it asserted, not written here. The count is how many separate times the claim was put to the test while these drawings were made.
- the program at b₂ = 2 has at least one feasible vertex ×33
- the program at b₂ = 2 is bounded — an objective that increases without limit has no optimal vertex to draw ×33
- the program at b₂ = 5/2 has at least one feasible vertex ×32
- the program at b₂ = 5/2 is bounded — an objective that increases without limit has no optimal vertex to draw ×32
- the program at b₁ = 2 has at least one feasible vertex ×31
- the program at b₁ = 2 is bounded — an objective that increases without limit has no optimal vertex to draw ×31
- the program at b₁ = 5/2 has at least one feasible vertex ×30
- the program at b₁ = 5/2 is bounded — an objective that increases without limit has no optimal vertex to draw ×30
- constraint row 1 constrains at least one variable ×3
- constraint row 1 has one coefficient per variable ×3
- the right-hand side is a list of 2 to 2 numbers ×2
- a program here has between two and five constraint rows ×1
- a rational is a whole numerator over a non-zero whole denominator ×1
- a rational is never divided by zero ×1
- an intersection is kept exactly when it satisfies every constraint ×1
- each entry of the right-hand side is a whole number between 0 and 400 ×1
- each piece's slope is the dual variable on that piece ×1
- every complementary product is exactly zero ×1
- every constraint coefficient is a whole number of size at most 40 ×1
- every dual certificate at this optimum gives the same price for the swept constraint ×1
- every feasible primal value is at most every feasible dual value ×1
- every objective coefficient is a whole number of size at most 40 ×1
- every pair of constraints was formed, not a selection of them ×1
- no dual variable and no reduced cost is negative ×1
- no feasible lattice point beats the best vertex ×1
- no slack and no variable is negative at the optimum ×1
- the constraint whose right-hand side is swept is a whole number between 1 and 2 ×1
- the drawn dual region is convex ×1
- the drawn primal region is convex ×1
- the dual certificate is worth exactly what the primal optimum is worth ×1
- the dual is drawn only for a program with two constraints — with more, the dual polytope has more than two variables and is not a polygon in the plane ×1
- the dual optimum is unique, so each constraint has one price — a degenerate optimum, with more than two constraints through one point, has a whole set of them and no single table of products ×1
- the dual program has at least one feasible vertex ×1
- the dual program is bounded — an objective that increases without limit has no optimal vertex to draw ×1
- the exact arithmetic stays inside the safe integer range ×1
- the exact optimum and the decimal one agree ×1
- the exact optimum at the top of the sweep and the decimal one agree ×1
- the feasible vertices are in convex position ×1
- the high end of the sweep is a whole number between 1 and 400 ×1
- the low end of the sweep is a whole number between 0 and 400 ×1
- the multipliers reproduce the objective exactly ×1
- the objective has one coefficient per variable ×1
- the objective is not identically zero ×1
- the optimal vertex has a dual certificate — a non-negative multiplier on each binding constraint ×1
- the optimal vertex's coordinates are labelled clear of every dot, every value and the axis ticks ×1
- the optimum has a dual certificate ×1
- the optimum is linear across this interval, so the drawn segment is exact ×1
- the polytope figure's mode is one of primal, dual, slack, shadow ×1
- the primal maximum and the dual minimum are the same number ×1
- the primal program has at least one feasible vertex ×1
- the primal program is bounded — an objective that increases without limit has no optimal vertex to draw ×1
- the reduced cost is the multiplier on the variable's own non-negativity ×1
- the slope of the optimum equals the dual variable for the swept constraint ×1
- the sweep produced at least one linear piece ×1
- the sweep runs over between two and sixty units of the right-hand side ×1
- the sweep solved the program once at every whole right-hand side ×1
- the two optima agree as decimals too ×1
- there is one breakpoint between consecutive pieces ×1
- there is one product per constraint and one per variable ×1
- weak duality was checked on the whole cross product of the two vertex lists ×1
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.
Two numbers that have to meet
Every linear program has a shadow — a second program built from the same numbers read the other way, whose minimum can never fall below the first's maximum. That much is a one-line calculation; the theorem is that the two numbers are always exactly equal.
AppliedWhat a constraint is worth
The rung below settled that a linear program and its dual reach the same number. This one asks what the dual's variables are, and the answer converts a solution into a rate for every constraint — piecewise constant, zero on the constraints that are not doing any work.