title: Defining specific set of values for 2 variables in PYOMO
body: <p>I am trying to assign material property using multiple variables. For example; density and conductivity are two decision variables for material_1, material_2 and material_3.</p>
  <p>I have to input the following information:</p>
  <pre><code>density of material_1 = 1000
  density of material_2 = 2000
  density of material_3 = 1500
  
  conductivity of material_1 = 250
  conductivity of material_2 = 400
  conductivity of material_3 = 100
  
  </code></pre>
  <p>The standard format for defining variables in Pyomo is given
  below:</p>
  <p><code>model.variable_1 = Var(bounds=(800,2000))</code></p>
  <p>The above code means variable_1 is a variable with lower bound = 800, and upper bound = 2000.</p>
  <p>But how can we <strong>define a variable with a specific set of values instead of a bound?</strong></p>
  <p>The idea is to input data values into the optimizer such that <strong>when it chooses a density value, it should also choose the conductivity value from the same material</strong>.</p>
  <p>How can we impose such a condition into pyomo framework? Can someone please help me with this?</p>