by 
Places a true or false sign at the intersection of a row and a column.
This is the basic instruction of zebra puzzles.
Alice is third.
Bob is wearing a yellow jersey.
Fifth doesn’t drink apple juice.
When a true sign is placed, the row and column of the intersection can be completed with false signs .
Designer
Place a true or false sign in the grid at a random location, according to programming. The choice of sign can be imposed or random.
If the instruction operates in isolated mode, the designer randomly selects an intersection whose row and column are empty of any sign (no true , no false , no Boolean).
Maximum number of instruction executions. It is recommended to end programs with a final instruction: PLACE false, to be repeated until resolved. Therefore, on the last instruction, you can set a high maximum, which will never be reached, such as 1000.
Generated formal proposals
a ∩ b = true
a ∩ b = false