Schedule algebra
Here is another look at the outcome table. First I complete the left column:
| condition on x | on y | replace \([a, b]\) with |
|---|---|---|
| \(x > b\) | \([a, b]\) | |
| \(x = b\) | \([a, x-1] [x, y]\) | |
| \(a < x < b\) | \(y < b\) | \([a, x-1] [x, y] [y+1,b]\) |
| \(a < x < b\) | \(y \ge b\) | \([a, x-1] [x, y]\) |
| \(a = x\) | \(y < b\) | \([x, y] [y+1, b]\) |
| \(a = x\) | \(y \ge b\) | \([x, y]\) |
| \(a > x\) | \(y < a\) | \([a, b]\) |
| \(a > x\) | \(y = a\) | \([x, y] [y+1, b]\) |
| \(a > x\) | \(b > y > a\) | \([x, y] [y+1, b]\) |
| \(a > x\) | \(b \le y\) | \([x, y]\) |
Then I reorder by number of elements in the replacement:
| condition on x | on y | replace \([a, b]\) with |
|---|---|---|
| \(x > b\) | \([a, b]\) | |
| \(a = x\) | \(y \ge b\) | \([x, y]\) |
| \(a > x\) | \(y < a\) | \([a, b]\) |
| \(a > x\) | \(b \le y\) | \([x, y]\) |
| \(x = b\) | \([a, x-1] [x, y]\) | |
| \(a < x < b\) | \(y \ge b\) | \([a, x-1] [x, y]\) |
| \(a = x\) | \(y < b\) | \([x, y] [y+1, b]\) |
| \(a > x\) | \(y = a\) | \([x, y] [y+1, b]\) |
| \(a > x\) | \(b > y > a\) | \([x, y] [y+1, b]\) |
| \(a < x < b\) | \(y < b\) | \([a, x-1] [x, y] [y+1,b]\) |
Then I will do some computations on a piece of paper (not shown here) to derive a simplification.