<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated by Fujitsu Interstage XWand B0254 -->
<!-- Generated by Broadridge Financial Solutions Inc -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:abf="http://abf/20260624" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink">
  <link:roleRef roleURI="http://xbrl.sec.gov/rr/role/ProspectusOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#ProspectusOnly"/>
  <link:roleRef roleURI="http://xbrl.sec.gov/oef/role/SeriesOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#SeriesOnly"/>
  <link:roleRef roleURI="http://xbrl.sec.gov/oef/role/ClassOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#ClassOnly"/>
  <link:roleRef roleURI="http://xbrl.sec.gov/rr/role/RiskOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#RiskOnly"/>
  <link:roleRef roleURI="http://xbrl.sec.gov/rr/role/PerformanceMeasureOnly" xlink:type="simple" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#PerformanceMeasureOnly"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/rr/role/ProspectusOnly">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_DocumentDomain" xlink:label="DocumentDomain"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_Dababerdeenmunicipalhighincomeetffyepro_2797Member" xlink:label="Dababerdeenmunicipalhighincomeetffyepro_2797Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="DocumentDomain" xlink:to="Dababerdeenmunicipalhighincomeetffyepro_2797Member" use="optional" order="1.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_Dababerdeenmunicipalhighincomeetffyesai_2798Member" xlink:label="Dababerdeenmunicipalhighincomeetffyesai_2798Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="DocumentDomain" xlink:to="Dababerdeenmunicipalhighincomeetffyesai_2798Member" use="optional" order="2.0"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/SeriesOnly">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2025/dei-2025.xsd#dei_EntityDomain" xlink:label="dei_EntityDomain"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_S000105855Member" xlink:label="S000105855Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="dei_EntityDomain" xlink:to="S000105855Member" use="optional" order="2.0"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/oef/role/ClassOnly">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_ShareClassDomain" xlink:label="ShareClassDomain"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_C000276651Member" xlink:label="C000276651Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="ShareClassDomain" xlink:to="C000276651Member" use="optional" order="2.0"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/rr/role/PerformanceMeasureOnly">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_PerformanceMeasureDomain" xlink:label="PerformanceMeasureDomain"/>
  </link:definitionLink>
  <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/rr/role/RiskOnly">
    <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/oef/2025/oef-2025.xsd#oef_AllRisksMember" xlink:label="oef_AllRisksMember"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FixedIncomeSecuritiesMember" xlink:label="us-gaap_FixedIncomeSecuritiesMember"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="us-gaap_FixedIncomeSecuritiesMember" order="11.0" xbrldt:closed="true"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MortgageBackedSecuritiesMember" xlink:label="us-gaap_MortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="us-gaap_MortgageBackedSecuritiesMember" order="15.0" xbrldt:closed="true"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollateralizedMortgageObligationsMember" xlink:label="us-gaap_CollateralizedMortgageObligationsMember"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="us-gaap_CollateralizedMortgageObligationsMember" order="16.0" xbrldt:closed="true"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember" xlink:label="us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="us-gaap_CommercialMortgageBackedSecuritiesMember" order="18.0" xbrldt:closed="true"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetBackedSecuritiesMember" xlink:label="us-gaap_AssetBackedSecuritiesMember"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="us-gaap_AssetBackedSecuritiesMember" order="20.0" xbrldt:closed="true"/>
    <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SovereignDebtSecuritiesMember" xlink:label="us-gaap_SovereignDebtSecuritiesMember"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="us-gaap_SovereignDebtSecuritiesMember" order="25.0" xbrldt:closed="true"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230512163Member" xlink:label="bench20230512163Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230512163Member" use="optional" order="14.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407126Member" xlink:label="bench20230407126Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407126Member" use="optional" order="15.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407127Member" xlink:label="bench20230407127Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407127Member" use="optional" order="16.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407101Member" xlink:label="bench20230407101Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407101Member" use="optional" order="17.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230512165Member" xlink:label="bench20230512165Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230512165Member" use="optional" order="18.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230714182Member" xlink:label="bench20230714182Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230714182Member" use="optional" order="19.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407153Member" xlink:label="bench20230407153Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407153Member" use="optional" order="110.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407133Member" xlink:label="bench20230407133Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407133Member" use="optional" order="111.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407106Member" xlink:label="bench20230407106Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407106Member" use="optional" order="112.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407107Member" xlink:label="bench20230407107Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407107Member" use="optional" order="113.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407135Member" xlink:label="bench20230407135Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407135Member" use="optional" order="114.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407109Member" xlink:label="bench20230407109Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407109Member" use="optional" order="115.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230512169Member" xlink:label="bench20230512169Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230512169Member" use="optional" order="116.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230714183Member" xlink:label="bench20230714183Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230714183Member" use="optional" order="117.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230512178Member" xlink:label="bench20230512178Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230512178Member" use="optional" order="118.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407115Member" xlink:label="bench20230407115Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407115Member" use="optional" order="119.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230512172Member" xlink:label="bench20230512172Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230512172Member" use="optional" order="120.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407117Member" xlink:label="bench20230407117Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407117Member" use="optional" order="121.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20260603232Member" xlink:label="bench20260603232Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20260603232Member" use="optional" order="122.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230512174Member" xlink:label="bench20230512174Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230512174Member" use="optional" order="123.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407149Member" xlink:label="bench20230407149Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407149Member" use="optional" order="124.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407159Member" xlink:label="bench20230407159Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407159Member" use="optional" order="125.0"/>
    <link:loc xlink:type="locator" xlink:href="abf-20260624.xsd#abf_bench20230407151Member" xlink:label="bench20230407151Member"/>
    <link:definitionArc xlink:type="arc" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="oef_AllRisksMember" xlink:to="bench20230407151Member" use="optional" order="126.0"/>
  </link:definitionLink>
</link:linkbase>
