diff --git a/dnet-pace-core/src/main/java/eu/dnetlib/pace/clustering/WordsSuffixPrefix.java b/dnet-pace-core/src/main/java/eu/dnetlib/pace/clustering/WordsSuffixPrefix.java
index 6086ac0..80459cb 100644
--- a/dnet-pace-core/src/main/java/eu/dnetlib/pace/clustering/WordsSuffixPrefix.java
+++ b/dnet-pace-core/src/main/java/eu/dnetlib/pace/clustering/WordsSuffixPrefix.java
@@ -22,6 +22,21 @@ public class WordsSuffixPrefix extends AbstractClusteringFunction {
     private Collection<String> suffixPrefix(String s, int len, int max) {
 
         final int words = s.split(" ").length;
+
+        // adjust the token length according to the number of words
+        switch (words) {
+            case 1:
+                return Sets.newLinkedHashSet();
+            case 2:
+                return doSuffixPrefix(s, len+2, max, words);
+            case 3:
+                return doSuffixPrefix(s, len+1, max, words);
+            default:
+                return doSuffixPrefix(s, len, max, words);
+        }
+    }
+
+    private Collection<String> doSuffixPrefix(String s, int len, int max, int words) {
         final Set<String> bigrams = Sets.newLinkedHashSet();
         int i = 0;
         while (++i < s.length() && bigrams.size() < max) {
diff --git a/pom.xml.releaseBackup b/pom.xml.releaseBackup
deleted file mode 100644
index d840af1..0000000
--- a/pom.xml.releaseBackup
+++ /dev/null
@@ -1,333 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
-
-    <modelVersion>4.0.0</modelVersion>
-
-    <groupId>eu.dnetlib</groupId>
-    <artifactId>dnet-dedup</artifactId>
-    <version>4.0.2-SNAPSHOT</version>
-
-    <packaging>pom</packaging>
-
-    <url>http://www.d-net.research-infrastructures.eu</url>
-
-    <licenses>
-        <license>
-            <name>The Apache Software License, Version 2.0</name>
-            <url>http://www.apache.org/licenses/LICENSE-2.0.txt</url>
-            <distribution>repo</distribution>
-            <comments>A business-friendly OSS license</comments>
-        </license>
-    </licenses>
-
-    <scm>
-        <developerConnection>scm:git:https://code-repo.d4science.org/D-Net/dnet-dedup.git</developerConnection>
-        <tag>HEAD</tag>
-    </scm>
-
-    <modules>
-        <module>dnet-pace-core</module>
-        <module>dnet-dedup-test</module>
-    </modules>
-
-    <issueManagement>
-        <system>Redmine</system>
-        <url>https://issue.openaire.research-infrastructures.eu/projects/openaire</url>
-    </issueManagement>
-
-
-
-    <distributionManagement>
-        <repository>
-            <id>dnet45-releases</id>
-            <name>D-Net 45 Releases</name>
-            <url>http://maven.research-infrastructures.eu/nexus/content/repositories/dnet45-releases</url>
-            <layout>default</layout>
-        </repository>
-    </distributionManagement>
-
-    <repositories>
-        <repository>
-            <id>dnet-deps</id>
-            <name>dnet-dependencies</name>
-            <url>http://maven.research-infrastructures.eu/nexus/content/repositories/dnet-deps</url>
-            <layout>default</layout>
-        </repository>
-        <repository>
-            <id>dnet45-releases</id>
-            <name>D-Net 45 Releases</name>
-            <url>http://maven.research-infrastructures.eu/nexus/content/repositories/dnet45-releases</url>
-            <layout>default</layout>
-            <snapshots>
-                <enabled>true</enabled>
-            </snapshots>
-        </repository>
-        <repository>
-            <id>dnet45-snapshots</id>
-            <name>D-Net 45 Snapshots</name>
-            <url>http://maven.research-infrastructures.eu/nexus/content/repositories/dnet45-snapshots</url>
-            <layout>default</layout>
-            <snapshots>
-                <enabled>true</enabled>
-            </snapshots>
-        </repository>
-
-        <repository>
-            <id>cloudera</id>
-            <name>Cloudera Repository</name>
-            <url>https://repository.cloudera.com/artifactory/cloudera-repos</url>
-            <releases>
-                <enabled>true</enabled>
-            </releases>
-            <snapshots>
-                <enabled>false</enabled>
-            </snapshots>
-        </repository>
-    </repositories>
-    <build>
-        <directory>target</directory>
-        <outputDirectory>target/classes</outputDirectory>
-        <finalName>${project.artifactId}-${project.version}</finalName>
-        <testOutputDirectory>target/test-classes</testOutputDirectory>
-
-
-
-
-        <!--*************************************************-->
-
-        <pluginManagement>
-            <plugins>
-
-                <plugin>
-                    <groupId>org.apache.maven.plugins</groupId>
-                    <artifactId>maven-compiler-plugin</artifactId>
-                    <version>3.6.0</version>
-                    <configuration>
-                        <source>1.8</source>
-                        <target>1.8</target>
-                        <encoding>${project.build.sourceEncoding}</encoding>
-                    </configuration>
-                </plugin>
-
-                <plugin>
-                    <groupId>org.apache.maven.plugins</groupId>
-                    <artifactId>maven-jar-plugin</artifactId>
-                    <version>3.0.2</version>
-                </plugin>
-
-                <plugin>
-                    <groupId>org.apache.maven.plugins</groupId>
-                    <artifactId>maven-source-plugin</artifactId>
-                    <version>3.0.1</version>
-                    <executions>
-                        <execution>
-                            <id>attach-sources</id>
-                            <phase>verify</phase>
-                            <goals>
-                                <goal>jar-no-fork</goal>
-                            </goals>
-                        </execution>
-                    </executions>
-                </plugin>
-
-                <plugin>
-                    <groupId>org.apache.maven.plugins</groupId>
-                    <artifactId>maven-surefire-plugin</artifactId>
-                    <version>2.19.1</version>
-                    <configuration>
-                        <redirectTestOutputToFile>true</redirectTestOutputToFile>
-                    </configuration>
-                </plugin>
-
-                <plugin>
-                    <groupId>org.apache.maven.plugins</groupId>
-                    <artifactId>maven-javadoc-plugin</artifactId>
-                    <version>2.10.4</version>
-                    <configuration>
-                        <detectLinks>true</detectLinks>
-                    </configuration>
-                </plugin>
-
-                <plugin>
-                    <groupId>org.apache.maven.plugins</groupId>
-                    <artifactId>maven-dependency-plugin</artifactId>
-                    <version>3.0.0</version>
-                </plugin>
-
-                <plugin>
-                    <groupId>org.apache.maven.plugins</groupId>
-                    <artifactId>maven-failsafe-plugin</artifactId>
-                    <version>2.13</version>
-                    <executions>
-                        <execution>
-                            <id>integration-test</id>
-                            <goals>
-                                <goal>integration-test</goal>
-                            </goals>
-                        </execution>
-                        <execution>
-                            <id>verify</id>
-                            <goals>
-                                <goal>verify</goal>
-                            </goals>
-                        </execution>
-                    </executions>
-                </plugin>
-
-            </plugins>
-        </pluginManagement>
-
-        <plugins>
-
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-release-plugin</artifactId>
-                <version>2.5.3</version>
-            </plugin>
-
-        </plugins>
-    </build>
-
-    <dependencyManagement>
-        <dependencies>
-            <dependency>
-                <groupId>edu.cmu</groupId>
-                <artifactId>secondstring</artifactId>
-                <version>1.0.0</version>
-            </dependency>
-            <dependency>
-                <groupId>org.antlr</groupId>
-                <artifactId>stringtemplate</artifactId>
-                <version>3.2</version>
-            </dependency>
-
-            <dependency>
-                <groupId>com.fasterxml.jackson.core</groupId>
-                <artifactId>jackson-databind</artifactId>
-                <version>${jackson.version}</version>
-            </dependency>
-
-            <dependency>
-                <groupId>com.fasterxml.jackson.dataformat</groupId>
-                <artifactId>jackson-dataformat-xml</artifactId>
-                <version>${jackson.version}</version>
-            </dependency>
-            <dependency>
-                <groupId>com.fasterxml.jackson.module</groupId>
-                <artifactId>jackson-module-jsonSchema</artifactId>
-                <version>${jackson.version}</version>
-            </dependency>
-
-
-
-            <dependency>
-                <groupId>org.apache.commons</groupId>
-                <artifactId>commons-math3</artifactId>
-                <version>3.6.1</version>
-            </dependency>
-
-            <dependency>
-                <groupId>com.google.guava</groupId>
-                <artifactId>guava</artifactId>
-                <version>${google.guava.version}</version>
-            </dependency>
-            <dependency>
-                <groupId>com.google.code.gson</groupId>
-                <artifactId>gson</artifactId>
-                <version>${google.gson.version}</version>
-            </dependency>
-
-            <dependency>
-                <groupId>org.apache.commons</groupId>
-                <artifactId>commons-lang3</artifactId>
-                <version>${commons.lang.version}</version>
-            </dependency>
-
-            <dependency>
-                <groupId>commons-io</groupId>
-                <artifactId>commons-io</artifactId>
-                <version>${commons.io.version}</version>
-            </dependency>
-            <dependency>
-                <groupId>commons-collections</groupId>
-                <artifactId>commons-collections</artifactId>
-                <version>${commons.collections.version}</version>
-            </dependency>
-            <dependency>
-                <groupId>commons-logging</groupId>
-                <artifactId>commons-logging</artifactId>
-                <version>${commons.logging.version}</version>
-            </dependency>
-            <dependency>
-                <groupId>org.apache.spark</groupId>
-                <artifactId>spark-core_2.11</artifactId>
-                <version>${spark.version}</version>
-                <scope>provided</scope>
-            </dependency>
-            <dependency>
-                <groupId>org.apache.spark</groupId>
-                <artifactId>spark-graphx_2.11</artifactId>
-                <version>${spark.version}</version>
-                <scope>provided</scope>
-            </dependency>
-            <dependency>
-                <groupId>org.apache.spark</groupId>
-                <artifactId>spark-sql_2.11</artifactId>
-                <version>${spark.version}</version>
-                <scope>provided</scope>
-            </dependency>
-            <dependency>
-                <groupId>junit</groupId>
-                <artifactId>junit</artifactId>
-                <version>${junit.version}</version>
-                <scope>test</scope>
-            </dependency>
-            <dependency>
-                <groupId>org.reflections</groupId>
-                <artifactId>reflections</artifactId>
-                <version>0.9.10</version>
-            </dependency>
-
-            <dependency>
-                <groupId>org.scala-lang</groupId>
-                <artifactId>scala-library</artifactId>
-                <version>${scala.version}</version>
-            </dependency>
-
-            <dependency>
-                <groupId>org.apache.oozie</groupId>
-                <artifactId>oozie-client</artifactId>
-                <version>5.1.0</version>
-            </dependency>
-            <dependency>
-                <groupId>com.jayway.jsonpath</groupId>
-                <artifactId>json-path</artifactId>
-                <version>2.4.0</version>
-            </dependency>
-
-
-        </dependencies>
-    </dependencyManagement>
-
-    <properties>
-
-        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
-
-        <google.gson.version>2.2.2</google.gson.version>
-        <google.guava.version>15.0</google.guava.version>
-
-        <spark.version>2.2.0</spark.version>
-        <jackson.version>2.6.6</jackson.version>
-
-        <commons.lang.version>3.5</commons.lang.version>
-        <commons.io.version>2.4</commons.io.version>
-        <commons.collections.version>3.2.1</commons.collections.version>
-        <commons.logging.version>1.1.3</commons.logging.version>
-
-        <junit.version>4.9</junit.version>
-        <scala.version>2.11.8</scala.version>
-
-        <maven.javadoc.failOnError>false</maven.javadoc.failOnError>
-    </properties>
-</project>
diff --git a/release.properties b/release.properties
deleted file mode 100644
index 70a3c40..0000000
--- a/release.properties
+++ /dev/null
@@ -1,22 +0,0 @@
-#release configuration
-#Thu Jul 02 17:06:39 CEST 2020
-scm.commentPrefix=[maven-release-plugin] 
-pushChanges=true
-project.rel.eu.dnetlib\:dnet-dedup-test=4.0.2
-scm.tag=dnet-dedup-4.0.2
-remoteTagging=true
-project.scm.eu.dnetlib\:dnet-dedup-test.empty=true
-projectVersionPolicyId=default
-scm.url=scm\:git\:https\://code-repo.d4science.org/D-Net/dnet-dedup.git
-scm.tagNameFormat=@{project.artifactId}-@{project.version}
-project.rel.eu.dnetlib\:dnet-dedup=4.0.2
-project.dev.eu.dnetlib\:dnet-pace-core=4.0.3-SNAPSHOT
-preparationGoals=clean verify
-project.scm.eu.dnetlib\:dnet-dedup.tag=HEAD
-project.scm.eu.dnetlib\:dnet-dedup.developerConnection=scm\:git\:https\://code-repo.d4science.org/D-Net/dnet-dedup.git
-exec.snapshotReleasePluginAllowed=false
-project.dev.eu.dnetlib\:dnet-dedup=4.0.3-SNAPSHOT
-project.scm.eu.dnetlib\:dnet-pace-core.empty=true
-project.dev.eu.dnetlib\:dnet-dedup-test=4.0.3-SNAPSHOT
-completedPhase=end-release
-project.rel.eu.dnetlib\:dnet-pace-core=4.0.2