code: package it.unibz.inf.ontop.model.term.functionsymbol.db.impl;
  
  import com.google.common.collect.ImmutableList;
  import it.unibz.inf.ontop.exception.MinorOntopInternalBugException;
  import it.unibz.inf.ontop.model.term.ImmutableExpression;
  import it.unibz.inf.ontop.model.term.ImmutableTerm;
  import it.unibz.inf.ontop.model.term.TermFactory;
  import it.unibz.inf.ontop.model.term.functionsymbol.InequalityLabel;
  import it.unibz.inf.ontop.model.type.DBTermType;
  
  import java.util.function.Function;
  
  import static it.unibz.inf.ontop.model.term.functionsymbol.InequalityLabel.*;
  
  
  public abstract class AbstractDBInequalityOperator extends DBBooleanFunctionSymbolImpl {
  
      private final String template;
      protected final InequalityLabel inequalityLabel;
  
      protected AbstractDBInequalityOperator(InequalityLabel inequalityLabel, String functionSymbolName,
                                             DBTermType rootDBTermType,
                                             DBTermType dbBoolean) {
          super(functionSymbolName, ImmutableList.of(rootDBTermType, rootDBTermType), dbBoolean);
          this.inequalityLabel = inequalityLabel;
          this.template = "(%s " + inequalityLabel.getMathString() + " %s)";
      }
  
      /**
       * Can be overridden
       */
      @Override
      public String getNativeDBString(ImmutableList<? extends ImmutableTerm> terms,
                                      Function<ImmutableTerm, String> termConverter, TermFactory termFactory) {
          return String.format(template, termConverter.apply(terms.get(0)), termConverter.apply(terms.get(1)));
      }
  
      @Override
      protected boolean tolerateNulls() {
          return false;
      }
  
      @Override
      public boolean isAlwaysInjectiveInTheAbsenceOfNonInjectiveFunctionalTerms() {
          return false;
      }
  
      @Override
      public boolean blocksNegation() {
          return false;
      }
  
      @Override
      public ImmutableExpression negate(ImmutableList<? extends ImmutableTerm> subTerms, TermFactory termFactory) {
          switch (inequalityLabel) {
              case LT:
                  return buildInequality(GTE, subTerms, termFactory);
              case LTE:
                  return buildInequality(GT, subTerms, termFactory);
              case GT:
                  return buildInequality(LTE, subTerms, termFactory);
              case GTE:
                  return buildInequality(LT, subTerms, termFactory);
              default:
                  throw new MinorOntopInternalBugException("Unexpected inequality label: " + inequalityLabel);
          }
      }
  
      protected abstract ImmutableExpression buildInequality(InequalityLabel inequalityLabel,
                                                             ImmutableList<? extends ImmutableTerm> subTerms,
                                                             TermFactory termFactory);
  
  
  }
  