The assume command sets variable properties and relationships between variables. A common use of the assume command is assume(a>0). This states that the symbol $a$ is assumed to be a positive real constant. Having made such an assumption, Maple routines are able to use this information to simplify expressions, for example, $\sqrt{{a}^{2}\cdot b}$to $a\cdot \sqrt{\left(b\right)}$, and evaluate inequalities, for example, is(a+1>0) returns true.
The cannot assume on a constant object error occurs when the expression on which to place the assumption does not contain a name on which to base the assumption, for example, a variable that has been assigned a constant value.