I am dealing with the situation where despite of specifying my variables `b1`

and `c`

to be greater than zero, Mathematica still returns the output with `Re(b1+c)`

```
In(1):= mat1 = Simplify(( {
{a - ( b1 + c)/2 I, d},
{d, a - (b2 - c )/2 I}
} ));
mat2 = ( {
{0, 0, 1, 0},
{0, 0, 0, 1},
{-1, 0, 0, 0},
{0, -1, 0, 0}
} );
MatrixForm(FullSimplify(( {
{Re(mat1((1))((1))),
Re(mat1((1))((2))), -Im(mat1((1))((1))), -Im(mat1((1))((2)))},
{Re(mat1((2))((1))),
Re(mat1((2))((2))), -Im(mat1((2))((1))), -Im(mat1((2))((2)))},
{Im(mat1((1))((1))), Im(mat1((1))((2))), Re(mat1((1))((1))),
Re(mat1((1))((2)))},
{Im(mat1((2))((1))), Im(mat1((2))((2))), Re(mat1((2))((1))),
Re(mat1((2))((2)))}
} ), {a >= 0, d >= 0, b1 >= 0, b2 >= 0, c >= 0}))
Out(3)//MatrixForm= !(
TagBox(
RowBox({"(", "", GridBox({
{"a", "d",
FractionBox(
RowBox({"b1", "+", "c"}), "2"), "0"},
{"d", "a", "0",
FractionBox(
RowBox({"b2", "-", "c"}), "2")},
{
RowBox({
RowBox({"-",
FractionBox("1", "2")}), " ",
RowBox({"Re", "(",
RowBox({"b1", "+", "c"}), ")"})}), "0", "a", "d"},
{"0",
RowBox({
FractionBox("1", "2"), " ",
RowBox({"(",
RowBox({
RowBox({"-", "b2"}), "+", "c"}), ")"})}), "d", "a"}
},
GridBoxAlignment->{
"Columns" -> {{Center}}, "ColumnsIndexed" -> {},
"Rows" -> {{Baseline}}, "RowsIndexed" -> {}},
GridBoxSpacings->{"Columns" -> {
Offset(0.27999999999999997`), {
Offset(0.7)},
Offset(0.27999999999999997`)}, "ColumnsIndexed" -> {}, "Rows" -> {
Offset(0.2), {
Offset(0.4)},
Offset(0.2)}, "RowsIndexed" -> {}}), "", ")"}),
Function(BoxForm`e$,
MatrixForm(BoxForm`e$))))
```