I want to know why below code show only 0 & 1 ???

```
constraint c1{
addr dist {(addr > 45):= 80,(addr < 45):= 20};
}
```

For full code : constraint 80 to 20 value - EDA Playground

But below one work properly

```
constraint c1{
addr>45 dist {1:= 80,0:= 20};
}
```

For full code : (1) - EDA Playground

In both constraint logic are right but first one constraint show only 1 & 0

*In reply to amir_sharfu:*

A **dist** constraint also behaves like a set membership **inside** operator constraint. The value on the LHS must be in the set of values on the RHS.

In your second constraint, the set of values on the RHS are 0 and 1, and the possible values on the LHS expression can only be 0 or 1. So this constraint does not *constrain* any values, just affects their distribution.

In your first constraint, the expressions on the RHS can only result in a 0 or 1, so that means the value on the LHS is constraint to only be 0 or 1. So addr can only be 0 or 1. Itâ€™s distribution does not make any sense.