In a previous paper of the author, the notion of global equivalence between
two deformable thermoelastic bodies B and B' was introduced. This equivale
nce is understood in the sense that a global thermokinetic process for B is
admissible (in the sense of Coleman and Noll) if and only if its counterpa
rt for B, according to a suitable bijective correspondence (k) over cap bet
ween B and B', also is admissible. In this case, B and B' are said to be gl
obally (k) over cap -equivalent. Global (k) over cap -equivalence does not
imply piecewise (k) over cap -equivalence, that is, the global equivalence
of arbitrary (k) over cap -corresponding subbodies of B and B'. Here we pre
sent two maximality theorems of global equivalence for a rigid heat-conduct
ing body B: one in the thermodynamic theory with no heat sources and the ot
her in the thermodynamic theory with heat supply. By these theorems, given
the rigid heat-conducting body B referred to its configuration (y) over cap
, in both the theories we characterize the constitutive equations for all r
igid heat conductors B' that have a configuration (y) over cap' with (y) ov
er cap'(B') = (y) over cap (B) and are globally (k) over cap -equivalent to
B for (k) over cap = (y) over cap (l-1) o (y) over cap.