     [x, y] = xy @dIvl.ends
     should.not.exist x.toDay.except(y.toDay)
     should.not.exist x.toDay.except(y.toDay)
-    (y.toDay.except(x.toDay).low  == y.toDay.low).should.be.true
-    (y.toDay.except(x.toDay).high == x.toDay.low).should.be.true
+    y.toDay.except(x.toDay).low.should.eql y.toDay.low
+    y.toDay.except(x.toDay).high.should.eql x.toDay.low
 
     [x, y] = xy @dIvl.begins
     should.not.exist x.toDay.except(y.toDay)
     should.not.exist x.toDay.except(y.toDay)
-    (y.toDay.except(x.toDay).low  == x.toDay.high).should.be.true
-    (y.toDay.except(x.toDay).high == y.toDay.high).should.be.true
+    y.toDay.except(x.toDay).low.should.eql x.toDay.high
+    y.toDay.except(x.toDay).high.should.eql y.toDay.high
 
   it 'should throw when the argument is a point', ->
     try

    d = new Uncertainty(80,90)
    e = 100

    x = new Interval(  b,  e)
    y = new Interval(a  ,c  )
    (x.except(y).low  == c).should.be.true
    (x.except(y).high == e).should.be.true
    (y.except(x).low  == a).should.be.true
    (y.except(x).high == b).should.be.true

    x = new Interval(a,b   )
    y = new Interval(  b,d )


    x = new Interval(  b,  e)
    y = new Interval(a  ,c  )
    x.intersect(y).should.eql new Interval(b, c)
    y.intersect(x).should.eql new Interval(b, c)

    x = new Interval(a,b   )
    y = new Interval(  b,d )
