Let
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X16302049&_mathId=si1.gif&_user=111111111&_pii=S0022314X16302049&_rdoc=1&_issn=0022314X&md5=8f0bc7ea82a970bfd09c55d99f04e746" title="Click to view the MathML source">P,Q∈Fq[X]∖{0}class="mathContainer hidden">class="mathCode"> be two coprime polynomials over the finite field
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X16302049&_mathId=si124.gif&_user=111111111&_pii=S0022314X16302049&_rdoc=1&_issn=0022314X&md5=b9264fbb0cd6ddc57c9e30dc465fe92f" title="Click to view the MathML source">Fqclass="mathContainer hidden">class="mathCode"> with
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X16302049&_mathId=si11.gif&_user=111111111&_pii=S0022314X16302049&_rdoc=1&_issn=0022314X&md5=4d8dafdf022fb32645b67ac6b75697f2" title="Click to view the MathML source">degP>degQclass="mathContainer hidden">class="mathCode">. We represent each polynomial
w over
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X16302049&_mathId=si124.gif&_user=111111111&_pii=S0022314X16302049&_rdoc=1&_issn=0022314X&md5=b9264fbb0cd6ddc57c9e30dc465fe92f" title="Click to view the MathML source">Fqclass="mathContainer hidden">class="mathCode"> by
class="formula" id="fm0010">
using a rational
base class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X16302049&_mathId=si5.gif&_user=111111111&_pii=S0022314X16302049&_rdoc=1&_issn=0022314X&md5=e18775548425ff80b18ef905fe9327bb" title="Click to view the MathML source">P/Qclass="mathContainer hidden">class="mathCode"> and
digits class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X16302049&_mathId=si6.gif&_user=111111111&_pii=S0022314X16302049&_rdoc=1&_issn=0022314X&md5=3c0274cac2d9c567c3d57a4aed0d93ac" title="Click to view the MathML source">si∈Fq[X]class="mathContainer hidden">class="mathCode"> satisfying
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X16302049&_mathId=si644.gif&_user=111111111&_pii=S0022314X16302049&_rdoc=1&_issn=0022314X&md5=f8313c89bc82ca7a6cb85f0c012a3c6e" title="Click to view the MathML source">degsi<degPclass="mathContainer hidden">class="mathCode">.
Digit expansions of this type are also defined for formal Laurent series over
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X16302049&_mathId=si124.gif&_user=111111111&_pii=S0022314X16302049&_rdoc=1&_issn=0022314X&md5=b9264fbb0cd6ddc57c9e30dc465fe92f" title="Click to view the MathML source">Fqclass="mathContainer hidden">class="mathCode">. We prove uniqueness and automatic properties of these expansions. Although the
ω -language of the possible digit strings is not regular, we are able to characterize the digit expansions of algebraic elements. In particular, we give a version of Christol's Theorem by showing that the digit string of the digit expansion of a formal Laurent series is automatic if and only if the series is algebraic over
class="mathmlsrc">class="formulatext stixSupport mathImg" data-mathURL="/science?_ob=MathURL&_method=retrieve&_eid=1-s2.0-S0022314X16302049&_mathId=si193.gif&_user=111111111&_pii=S0022314X16302049&_rdoc=1&_issn=0022314X&md5=ab21ee811c9f8af161d6673fc9a73037" title="Click to view the MathML source">Fq[X]class="mathContainer hidden">class="mathCode">. Finally, we study relations between digit expansions of formal Laurent series and a finite fields version of Mahler's 3/2-problem.