On 6 Nov 2020, at 15:12, stephan <stephan@stack.nl> wrote:

Replacing BTNGVariable>>#nextValue by

nextValue
    | nextValue |
    self currentValue
        ifNotNil: [valuesToExplore remove: self currentValue].
    nextValue := self valuesToExplore ifEmpty: [ nil ]
                ifNotEmpty: [self valuesToExplore anyOne].
    self currentValue: nextValue.
    ^ nextValue

returning nil instead of self when there are no more new values
makes the tests pass in BackTalkNG-Noury.20.mcz (Pharo 9)

That version looks like it is work in progress but has one working
solver.

Stephan