**Defined in theory: Thermal-system****Source code: thermal-system.ol**

**Documentation:**the class of all types of matter

**Subclass-Of:**Entity, Structural-element-model**Arity:**1**Has-Quantity-Function:**- Critical-density, Critical-pressure, Critical-temperature, Ideal-gas-constant, Ideal-gas-p, Ideal-specific-heat, Molecular-weight, Reference-temperature, Saturation-pressure, Saturation-temperature

**Critical-Density:***Slot-Cardinality:*1*Slot-Documentation:*the density of the substance at its critical point

**Critical-Pressure:***Slot-Cardinality:*1*Slot-Documentation:*the pressure at the critical point of the substance

**Critical-Temperature:***Slot-Cardinality:*1*Slot-Documentation:*the maximum temperature at which liquid and vapor phases can coexist in equilibrium

**Ideal-Gas-Constant:***Slot-Cardinality:*1*Slot-Documentation:*the gas constant (universal gas constant / molecular weight) of the substance when it is modeled as ideal gas

**Ideal-Gas-P:***Slot-Cardinality:*1*Slot-Documentation:*the attribute indicating that the particular instance of the substance can be regarded as ideal gas

**Ideal-Specific-Heat:***Slot-Cardinality:*1*Slot-Documentation:*the specific heat of the substance when it is modeled as ideal gas

**Molecular-Weight:***Slot-Cardinality:*1*Slot-Documentation:*the molecular weight of the substance

**Reference-Temperature:***Slot-Cardinality:*1*Slot-Documentation:*the temperature of the reference state, which is the thermodynamic state with respect to which the values of the state variables, internal energy, specific enthalpy, and specific entropy in all other states are computed

**Saturation-Pressure:***Slot-Cardinality:*1*Slot-Documentation:*the pressure at which a phase change takes place at a given temperature

**Saturation-Temperature:***Slot-Cardinality:*1*Slot-Documentation:*the temperature at which a phase change takes place at a given pressure

(Forall (?Self ?Time) (<=> (Active ?Time Substance ?Self) (And (Substance ?Self) (Active ?Time Structural-Element-Model ?Self)))) (=> (Substance ?Self) (And (Quantity.Dimension (Saturation-Pressure ?Self) Pressure-Dimension) (Quantity.Dimension (Saturation-Temperature ?Self) Temperature-Dimension) (Quantity.Dimension (Ideal-Specific-Heat ?Self) Specific-Energy-Dimension) (Quantity.Dimension (Molecular-Weight ?Self) Amount-Dimension) (Quantity.Dimension (Critical-Temperature ?Self) Temperature-Dimension) (Quantity.Dimension (Critical-Pressure ?Self) Pressure-Dimension) (Quantity.Dimension (Critical-Density ?Self) Density-Dimension) (Quantity.Dimension (Reference-Temperature ?Self) Temperature-Dimension)))