// no worky
for (var didx = 0; didx < domains[idx].Count; ++didx) {
    var domainValue = domains[idx][didx];
    if (value == domainValue || OptMath.Abs(domainValue - value) == OptMath.Abs(current - idx)) {
        domains[idx][didx] = -1;
    }
}
domains[idx].RemoveAll((x) => x == -1);
 
// worky
domains[idx] = (
    from domainValue in domains[idx]
    where domainValue != value
    where OptMath.Abs(domainValue - value) != OptMath.Abs(current - idx)
    select domainValue
).ToList();

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