diff --git a/README.md b/README.md
index 0dcf831..39c2bb5 100644
--- a/README.md
+++ b/README.md
@@ -110,7 +110,8 @@ $qb->bind('your data', 'your-bind-id')
     - [Subqueries](docs/core-concepts/subqueries.md): how to create subqueries, joins etc.
 - Core Concepts
     - [Terminology](docs/core-concepts/terminology.md): definitions of terms used in the documentation 
-    - [Data binding](docs/core-concepts/data-binding.md): How to inject external data and collections 
+    - [Data binding](docs/core-concepts/data-binding.md): How to inject external data and collections
+    - [Predicates](docs/core-concepts/predicates.md): How to use predicates in filter clauses and functions
     - [Subqueries](docs/core-concepts/subqueries.md): Subquery creation
 
 ## References & resources 
diff --git a/docs/api/functions.md b/docs/api/functions.md
index 6f7f140..3108bd6 100644
--- a/docs/api/functions.md
+++ b/docs/api/functions.md
@@ -20,8 +20,16 @@ $qb->for('i', '1..100')
 ## ArangoSearch functions
 | Description           | AQL Function |
 | :-------------------- | :-------------------------------------------------------------------------------------------- |
-| analyzer(string|array $leftOperand, $comparisonOperand, $rightOperand, $analyzer) | [ANALYZER(expr, analyzer)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#analyzer) |
-| boost(string|array $leftOperand, $comparisonOperand, $rightOperand, $analyzer) | [BOOST(expr, boost)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#boost) |
+| analyzer($leftOperand, $comparisonOperand, $rightOperand, $analyzer) | [ANALYZER(expr, analyzer)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#analyzer) |
+| bm25($doc, $k = null,$b = null) | [BM25(doc, k, b)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#bm25) |
+| boost($leftOperand, $comparisonOperand, $rightOperand, $analyzer) | [BOOST(expr, boost)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#boost) |
+| exists($path,$type = null) | [EXISTS(path)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#exists) |
+| inRange($path, $low, $high, $includeLow, $includeHigh) | [IN_RANGE(path, low, high, includeLow, includeHigh)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#in_range) |
+| levenshteinMatch($path, $target, $distance, $transpositions, $maxTerms, $prefix) | [LEVENSHTEIN_MATCH(path, target, distance, transpositions, maxTerms, prefix)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#levenshtein_match) |
+| like($path, $search)| [LIKE(path, search)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#like) |
+| nGramMatch($path, $target, $threshold, $analyzer) | [NGRAM_MATCH(path, target, threshold, analyzer)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#ngram_match) |
+| phrase(path, $phrasePart1, $skipTokens1, ... $phrasePartN, $skipTokensN ], $analyzer) | [PHRASE(path, [ phrasePart1, skipTokens1, ... phrasePartN, skipTokensN ], analyzer)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#phrase) |
+| tfidf($doc, $normalize) | [TFIDF(doc, normalize)](https://www.arangodb.com/docs/stable/aql/functions-arangosearch.html#tfidf) |
 
 
 ## Array functions
diff --git a/docs/core-concepts/predicates.md b/docs/core-concepts/predicates.md
new file mode 100644
index 0000000..8b062b5
--- /dev/null
+++ b/docs/core-concepts/predicates.md
@@ -0,0 +1,101 @@
+# Using predicates
+Predicates are conditional expressions that return a boolean on evaluation.
+Commonly written as `$leftOperand $comparisonOperator $rightOperand` for example: `true !== false`
+
+Predicates are used by the following clauses: filter, prune and search;
+as well as functions such as: analyzer and boost.
+
+## Singular predicates
+You can use the following syntax' to build predicates:
+
+### Basic:
+`$leftOperand, $comparisonOperator, $rightOperand`
+
+**Example: find active users**
+```php
+$qb->for('u', 'users')->filter('u.active', '==', true)->return('u'); 
+```
+resolves to :
+```aql
+FOR u IN users FILTER u.active == true RETURN u 
+```
+
+### without the rightOperand
+When you exclude the rightOperand a null value will be assumed.
+`$leftOperand, $comparisonOperator` resolves to `$leftOperand $comparisonOperator null`
+
+**Example: find users that don't have their age set.**
+```php
+$qb->for('u', 'users')->filter('u.age', '==')->return('u'); 
+```
+resolves to :
+```aql
+FOR u IN users FILTER u.active == null RETURN u 
+``` 
+
+### leftOperand only
+When just supplying the leftOperand the operator and rightOperand will be left blank.
+This useful to resolve the result of a function or subquery.
+
+Note that other values such as arrays or scalars always resolve to tru
+**Example: find users that have their age set.**
+```php
+$qb->for('u', 'users')->filter('u.age')->return('u'); 
+```
+resolves to :
+```aql
+FOR u IN users FILTER u.active RETURN u 
+``` 
+
+## Predicate groups
+You can combine multiple predicates by grouping them in arrays.
+**Example: get users whose age is between 17 and 68.**
+```php
+$qb->for('u', 'users')
+    ->filter([
+        ['u.age', '>=', 18],
+        ['u.age', '<=', 67]
+    ])
+    ->return('u');
+```
+resolves to :
+```aql
+FOR u IN users FILTER u.age >= 18 AND u.age <= 67 RETURN u 
+``` 
+**Note:** predicate group detect is quite simplistic. A leftOperand that is an array
+is assumed to be a predicate instead. If you need to use an array in the leftOperand positon use a PredicateExpression
+```php
+use LaravelFreelancerNL\FluentAQL\Expressions\PredicateExpression;
+
+// ...
+
+$qb->FILTER([
+        new PredicateExpression([1, 3, 4], 'ANY IN', [ 4, 5, 6 ]),
+        [false, '!==', true]
+    ]);
+```
+resolves to :
+```aql
+FILTER [1, 3, 4] ANY IN [ 4, 5, 6 ] AND false !== true  
+``` 
+
+### Changing the logical operator between groups:
+You can specify a logicalOperator for a predicate which will define its relation
+to the preceding predicate.
+
+In the previous example the predicates where combined with an 'AND' logical operator.
+By adding an 'OR' operator to the second predicate you change this default.
+
+**Example: get users whose age is not between 17 and 68.**
+```php
+$qb->for('u', 'users')
+    ->filter([
+        ['u.age', '<=', 18],
+        ['u.age', '>=', 67, 'OR']
+    ])
+    ->return('u');
+```
+resolves to :
+```aql
+FOR u IN users FILTER u.age <= 18 OR u.age >= 67 RETURN u 
+``` 
diff --git a/src/AQL/HasArangoSearchFunctions.php b/src/AQL/HasArangoSearchFunctions.php
index 46117ee..ea5662e 100644
--- a/src/AQL/HasArangoSearchFunctions.php
+++ b/src/AQL/HasArangoSearchFunctions.php
@@ -222,7 +222,7 @@ public function like(
      * @param null|string|object $analyzer
      * @return FunctionExpression
      */
-    public function ngramMatch(
+    public function nGramMatch(
         mixed $path,
         mixed $target,
         mixed $threshold = null,
diff --git a/tests/Unit/AQL/ArangoSearchFunctionsTest.php b/tests/Unit/AQL/ArangoSearchFunctionsTest.php
index 74e8c32..f2ed4b6 100644
--- a/tests/Unit/AQL/ArangoSearchFunctionsTest.php
+++ b/tests/Unit/AQL/ArangoSearchFunctionsTest.php
@@ -248,7 +248,7 @@ public function testNgramMatch()
     {
         $qb = new QueryBuilder();
         $qb->for('doc', 'viewName')
-            ->search($qb->ngramMatch("doc.text", "quick fox"))
+            ->search($qb->nGramMatch("doc.text", "quick fox"))
             ->return('doc.text');
 
         self::assertEquals(
@@ -262,7 +262,7 @@ public function testNgramMatchOptionalArgs()
     {
         $qb = new QueryBuilder();
         $qb->for('doc', 'viewName')
-            ->search($qb->ngramMatch("doc.text", "quick fox", 0.8, "bigram"))
+            ->search($qb->nGramMatch("doc.text", "quick fox", 0.8, "bigram"))
             ->return('doc.text');
 
         self::assertEquals(