In most circumstances, arithmetic constraints maintain bounds consistency
and detect bounds entailment and disentailment. There are cases where a
bounds consistency maintaining constraint may detect a contradiction when
the constraint is not yet bounds-disentailed, as the following example
illustrates. Note that

maintains
domain consistency if both arguments are constants or variables:
`X` #\= `Y`

| ?-X+Y #= Z, X=1, Z=6, Y in 1..10, Y #\= 5.no | ?-X+Y #= Z #<=> B, X=1, Z=6, Y in 1..10, Y #\= 5.X = 1, Z = 6, Y in(1..4)\/(6..10), B in 0..1

Since `1+5#=6`

holds, `X+Y #= Z`

is not bounds-disentailed,
although any attempt to make it bounds-consistent wrt. the store
results in a contradictory store.

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