# What is the difference between the algorithm value "ignore" and the option "nullMatch" set to false?

## Using the algorithm value `ignore`

The search algorithms can be controlled by setting the `type` field to a specific value. If the `type` field is set to `ignore`, the algorithm will be configured to ignore the attribute in the search, and any matches will be returned regardless of the value of the attribute. If the `type` field is set to any other value, the algorithm will be configured to consider the attribute in the search and only return matches with the specified attribute value.

This applies to any attribute that can be used in a search query, such as dates of birth, nationalities, or addresses.

For example, setting the `type` field to `same_year` for the `datesOfBirth` attribute will only return matches **with the same year of birth** as the search query, while setting the `type` field to `ignore` for the `datesOfBirth` attribute will return matches **regardless of their date of birth**.

The following examples demonstrate how the `type` field of the `dateOfBirthAlgo` algorithm can be used to control the behavior of the search.

### Example with a specified algorithm value

In the first example, the `dateOfBirthAlgo` is set to `same_year`. In this case, no match is found when searching for the individual named 'Abu Husayn' on the USA list because the API only considers matches where the year of birth is the same.

```json
{
	"queries": [
		{
			"sourceData": [
				{
					"names": [
						{
							"fullName": "Abu Husayn"
						}
					],
					"datesOfBirth": [
						{
							"date": "1979-04-02"
						}
					]
				}
			],
			"targetData": [
				{
					"datasets": [
						{
							"label": "USA"
						}
					]
				}
			],
			"threshold": 0.85,
			"dateOfBirthAlgo": {
				"type": "same_year"
			}
		}
	]
}
```

As stated above, the search does not return any matches because it does not find any individuals with the same name and year of birth on the USA list.

```json
{
	"responseHeader": {
		"requestID": "GEN2054093905-1670834053278",
		"responded": "2022-12-12T08:34:13.278Z"
	}
}
```

### Example with the algorithm value `ignore`

In the second example, the `dateOfBirthAlgo` is set to `ignore`, which means that the API will not use the date of birth as a criterion for searching the individual on the USA list. Instead, the API will only consider matches based on the full name.

```json
{
	"queries": [
		{
			"sourceData": [
				{
					"names": [
						{
							"fullName": "Abu Husayn"
						}
					],
					"datesOfBirth": [
						{
							"date": "1979-04-02"
						}
					]
				}
			],
			"targetData": [
				{
					"datasets": [
						{
							"label": "USA"
						}
					]
				}
			],
			"threshold": 0.85,
			"dateOfBirthAlgo": {
				"type": "ignore"
			}
		}
	]
}
```

This time, two matches were found.

```json
{
	"responseHeader": {
		"requestID": "GEN2054093905-1670834263596",
		"responded": "2022-12-12T08:37:43.596Z"
	},
	"results": [
		{
			"matchType": "st_match",
			"score": 1.00,
			"matchingNames": [
				{
					"fullName": "ABU HUSAYN",
					"normalized": "abu husayn"
				}
			],
			"sourceData": [
				{
					"entityType": "unknown",
					"names": [
						{
							"fullName": "Abu Husayn",
							"normalized": "abu husayn"
						}
					],
					"cultureCodes": [
						"ar"
					]
				}
			],
			"targetData": [
				{
					"dataID": "31971",
					"entityType": "individual",
					"names": [
						{
							"fullName": "AL-MADANI, Yusuf",
							"normalized": "al madani yusuf"
						},
						{
							"fullName": "AL-MADANI, Yusif",
							"normalized": "al madani yusuf"
						},
						{
							"fullName": "AL-MADANI, Youssef",
							"normalized": "al madani yusuf"
						},
						{
							"fullName": "AL-MADANI, Yousef Ahssan Ismail",
							"normalized": "al madani yusuf ahssan ismael"
						},
						{
							"fullName": "ABU HUSAYN",
							"normalized": "abu husayn"
						}
					],
					"sex": "m",
					"cultureCodes": [
						"ar"
					],
					"datesOfBirth": [
						{
							"date": "1977"
						}
					],
					"addresses": [
						{
							"country": "YE"
						}
					],
					"placesOfBirth": [
						{
							"city": "Muhatta Directorate",
							"country": "YE"
						}
					],
					"active": true,
					"keywords": [
						"SDGT",
						"Specially Designated Nationals (SDN) - Treasury Department"
					],
					"sources": [
						"Specially Designated Nationals (SDN) - Treasury Department",
						"https://home.treasury.gov/policy-issues/financial-sanctions/specially-designated-nationals-and-blocked-persons-list-sdn-human-readable-lists",
						"https://www.treasury.gov/resource-center/sanctions/SDN-List/Pages/default.aspx"
					],
					"label": "USA",
					"revision": 4968,
					"created": "2021-09-30T01:05:02.866",
					"updated": "2022-12-12T08:06:01.204",
					"lastMatched": "2021-09-30T01:05:02.866",
					"lastChecked": "2021-09-30T01:05:02.866"
				}
			]
		},
		{
			"matchType": "st_match",
			"score": 0.98,
			"matchingNames": [
				{
					"fullName": "HUSAYN, Abu",
					"normalized": "husayn abu"
				}
			],
			"sourceData": [
				{
					"entityType": "unknown",
					"names": [
						{
							"fullName": "Abu Husayn",
							"normalized": "abu husayn"
						}
					],
					"cultureCodes": [
						"ar"
					]
				}
			],
			"targetData": [
				{
					"dataID": "28571",
					"entityType": "individual",
					"names": [
						{
							"fullName": "AL-HAMIDAWI, Ahmad",
							"normalized": "al hamidawi ahmad"
						},
						{
							"fullName": "AL-HAMIDAWI, Ahmad Muhsin Faraj",
							"normalized": "al hamidawi ahmad muhsin faraj"
						},
						{
							"fullName": "AL-SAEDI, Ahmed Kadhim Raheem",
							"normalized": "al saedi ahmad kadhim raheem"
						},
						{
							"fullName": "AL-SA'IDI, Ahmad Kazim Rahim",
							"normalized": "al saidi ahmad kazim rahim"
						},
						{
							"fullName": "HUSAYN, Abu",
							"normalized": "husayn abu"
						}
					],
					"sex": "m",
					"cultureCodes": [
						"ar"
					],
					"nationalities": [
						{
							"country": "IQ"
						}
					],
					"datesOfBirth": [
						{
							"date": "1974-03-25"
						}
					],
					"addresses": [
						{
							"city": "Baghdad",
							"country": "IQ"
						}
					],
					"placesOfBirth": [
						{
							"country": "IQ"
						}
					],
					"active": true,
					"keywords": [
						"SDGT",
						"Specially Designated Nationals (SDN) - Treasury Department"
					],
					"sources": [
						"Specially Designated Nationals (SDN) - Treasury Department",
						"https://home.treasury.gov/policy-issues/financial-sanctions/specially-designated-nationals-and-blocked-persons-list-sdn-human-readable-lists",
						"https://www.treasury.gov/resource-center/sanctions/SDN-List/Pages/default.aspx"
					],
					"label": "USA",
					"revision": 4968,
					"created": "2021-09-30T01:05:02.764",
					"updated": "2022-12-12T08:06:00.172",
					"lastMatched": "2021-09-30T01:05:02.764",
					"lastChecked": "2021-09-30T01:05:02.764"
				}
			]
		}
	]
}
```

When analyzing the results, we can notice that the first match comes with a date of birth equal to `1977` while the second one has a date of birth equal to `1974-03-25`. Both years of birth are different from that of the individual sent in the search request. This explains why no match was returned in the first example.

## Using the algorithm option `nullMatch`

The `nullMatch` option is used to specify how search algorithms should handle empty or missing attributes in the watchlists. This option allows the search to be more flexible and consider matches even if some attributes are not provided or are empty. This can be useful in situations where the information in the watchlists is incomplete or not fully known, and the search needs to be able to handle these cases.

When `nullMatch` is either not provided or set to `true` in a query, the search will consider attributes that are missing or empty as a match, whereas when it is set to `false`, these attributes will not be considered a match.

### Example with the algorithm option `nullMatch` set to `false`

For example, if a search query is looking for an Iraqi (IQ) national named 'Abu Husayn' on the USA list and the `nullMatch` option associated with the `nationalityAlgo` is set to `false`, the search will only return a match if the individual's nationality is explicitly listed as `IQ`.

```json
{
	"queries": [
		{
			"sourceData": [
				{
					"names": [
						{
							"fullName": "Abu Husayn"
						}
					],
					"nationalities": [
						{
							"country": "IQ"
						}
					]
				}
			],
			"targetData": [
				{
					"datasets": [
						{
							"label": "USA"
						}
					]
				}
			],
			"threshold": 0.85,
			"nationalityAlgo": {
				"type": "same_country",
				"nullMatch": false
			}
		}
	]
}
```

In the situation where `nullMatch` is set to `false`, only one match is found.

```json
{
	"responseHeader": {
		"requestID": "GEN2054093905-1670836810880",
		"responded": "2022-12-12T09:20:10.880Z"
	},
	"results": [
		{
			"matchType": "st_match",
			"score": 0.98,
			"matchingNames": [
				{
					"fullName": "HUSAYN, Abu",
					"normalized": "husayn abu"
				}
			],
			"sourceData": [
				{
					"entityType": "unknown",
					"names": [
						{
							"fullName": "Abu Husayn",
							"normalized": "abu husayn"
						}
					],
					"cultureCodes": [
						"ar"
					],
					"nationalities": [
						{
							"country": "IQ",
							"normalized": "IQ"
						}
					]
				}
			],
			"targetData": [
				{
					"dataID": "28571",
					"entityType": "individual",
					"names": [
						{
							"fullName": "AL-HAMIDAWI, Ahmad",
							"normalized": "al hamidawi ahmad"
						},
						{
							"fullName": "AL-HAMIDAWI, Ahmad Muhsin Faraj",
							"normalized": "al hamidawi ahmad muhsin faraj"
						},
						{
							"fullName": "AL-SAEDI, Ahmed Kadhim Raheem",
							"normalized": "al saedi ahmad kadhim raheem"
						},
						{
							"fullName": "AL-SA'IDI, Ahmad Kazim Rahim",
							"normalized": "al saidi ahmad kazim rahim"
						},
						{
							"fullName": "HUSAYN, Abu",
							"normalized": "husayn abu"
						}
					],
					"sex": "m",
					"cultureCodes": [
						"ar"
					],
					"nationalities": [
						{
							"country": "IQ"
						}
					],
					"datesOfBirth": [
						{
							"date": "1974-03-25"
						}
					],
					"addresses": [
						{
							"city": "Baghdad",
							"country": "IQ"
						}
					],
					"placesOfBirth": [
						{
							"country": "IQ"
						}
					],
					"active": true,
					"keywords": [
						"SDGT",
						"Specially Designated Nationals (SDN) - Treasury Department"
					],
					"sources": [
						"Specially Designated Nationals (SDN) - Treasury Department",
						"https://home.treasury.gov/policy-issues/financial-sanctions/specially-designated-nationals-and-blocked-persons-list-sdn-human-readable-lists",
						"https://www.treasury.gov/resource-center/sanctions/SDN-List/Pages/default.aspx"
					],
					"label": "USA",
					"revision": 4969,
					"created": "2021-09-30T01:05:02.764",
					"updated": "2022-12-12T09:06:38.826",
					"lastMatched": "2021-09-30T01:05:02.764",
					"lastChecked": "2021-09-30T01:05:02.764"
				}
			]
		}
	]
}
```

### Example with the algorithm option `nullMatch` set to `true`

Now if `nullMatch` is set to `true` or not provided, the same search will also return a match if the individual's nationality is not specified in the list of attributes.

```json
{
	"queries": [
		{
			"sourceData": [
				{
					"names": [
						{
							"fullName": "Abu Husayn"
						}
					],
					"nationalities": [
						{
							"country": "IQ"
						}
					]
				}
			],
			"targetData": [
				{
					"datasets": [
						{
							"label": "USA"
						}
					]
				}
			],
			"threshold": 0.85,
			"nationalityAlgo": {
				"type": "same_country",
				"nullMatch": true
			}
		}
	]
}
```

In the situation where `nullMatch` is set to `true`, the search finds two matches.

```json
{
	"responseHeader": {
		"requestID": "GEN2054093905-1670842976944",
		"responded": "2022-12-12T11:02:56.944Z"
	},
	"results": [
		{
			"matchType": "st_match",
			"score": 1.00,
			"matchingNames": [
				{
					"fullName": "ABU HUSAYN",
					"normalized": "abu husayn"
				}
			],
			"sourceData": [
				{
					"entityType": "unknown",
					"names": [
						{
							"fullName": "Abu Husayn",
							"normalized": "abu husayn"
						}
					],
					"cultureCodes": [
						"ar"
					],
					"nationalities": [
						{
							"country": "IQ",
							"normalized": "IQ"
						}
					]
				}
			],
			"targetData": [
				{
					"dataID": "31971",
					"entityType": "individual",
					"names": [
						{
							"fullName": "AL-MADANI, Yusuf",
							"normalized": "al madani yusuf"
						},
						{
							"fullName": "AL-MADANI, Yusif",
							"normalized": "al madani yusuf"
						},
						{
							"fullName": "AL-MADANI, Youssef",
							"normalized": "al madani yusuf"
						},
						{
							"fullName": "AL-MADANI, Yousef Ahssan Ismail",
							"normalized": "al madani yusuf ahssan ismael"
						},
						{
							"fullName": "ABU HUSAYN",
							"normalized": "abu husayn"
						}
					],
					"sex": "m",
					"cultureCodes": [
						"ar"
					],
					"datesOfBirth": [
						{
							"date": "1977"
						}
					],
					"addresses": [
						{
							"country": "YE"
						}
					],
					"placesOfBirth": [
						{
							"city": "Muhatta Directorate",
							"country": "YE"
						}
					],
					"active": true,
					"keywords": [
						"SDGT",
						"Specially Designated Nationals (SDN) - Treasury Department"
					],
					"sources": [
						"Specially Designated Nationals (SDN) - Treasury Department",
						"https://home.treasury.gov/policy-issues/financial-sanctions/specially-designated-nationals-and-blocked-persons-list-sdn-human-readable-lists",
						"https://www.treasury.gov/resource-center/sanctions/SDN-List/Pages/default.aspx"
					],
					"label": "USA",
					"revision": 4970,
					"created": "2021-09-30T01:05:02.866",
					"updated": "2022-12-12T10:06:03.700",
					"lastMatched": "2021-09-30T01:05:02.866",
					"lastChecked": "2021-09-30T01:05:02.866"
				}
			]
		},
		{
			"matchType": "st_match",
			"score": 0.98,
			"matchingNames": [
				{
					"fullName": "HUSAYN, Abu",
					"normalized": "husayn abu"
				}
			],
			"sourceData": [
				{
					"entityType": "unknown",
					"names": [
						{
							"fullName": "Abu Husayn",
							"normalized": "abu husayn"
						}
					],
					"cultureCodes": [
						"ar"
					],
					"nationalities": [
						{
							"country": "IQ",
							"normalized": "IQ"
						}
					]
				}
			],
			"targetData": [
				{
					"dataID": "28571",
					"entityType": "individual",
					"names": [
						{
							"fullName": "AL-HAMIDAWI, Ahmad",
							"normalized": "al hamidawi ahmad"
						},
						{
							"fullName": "AL-HAMIDAWI, Ahmad Muhsin Faraj",
							"normalized": "al hamidawi ahmad muhsin faraj"
						},
						{
							"fullName": "AL-SAEDI, Ahmed Kadhim Raheem",
							"normalized": "al saedi ahmad kadhim raheem"
						},
						{
							"fullName": "AL-SA'IDI, Ahmad Kazim Rahim",
							"normalized": "al saidi ahmad kazim rahim"
						},
						{
							"fullName": "HUSAYN, Abu",
							"normalized": "husayn abu"
						}
					],
					"sex": "m",
					"cultureCodes": [
						"ar"
					],
					"nationalities": [
						{
							"country": "IQ"
						}
					],
					"datesOfBirth": [
						{
							"date": "1974-03-25"
						}
					],
					"addresses": [
						{
							"city": "Baghdad",
							"country": "IQ"
						}
					],
					"placesOfBirth": [
						{
							"country": "IQ"
						}
					],
					"active": true,
					"keywords": [
						"SDGT",
						"Specially Designated Nationals (SDN) - Treasury Department"
					],
					"sources": [
						"Specially Designated Nationals (SDN) - Treasury Department",
						"https://home.treasury.gov/policy-issues/financial-sanctions/specially-designated-nationals-and-blocked-persons-list-sdn-human-readable-lists",
						"https://www.treasury.gov/resource-center/sanctions/SDN-List/Pages/default.aspx"
					],
					"label": "USA",
					"revision": 4970,
					"created": "2021-09-30T01:05:02.764",
					"updated": "2022-12-12T10:06:02.691",
					"lastMatched": "2021-09-30T01:05:02.764",
					"lastChecked": "2021-09-30T01:05:02.764"
				}
			]
		}
	]
}
```

The first match is the same match which is found when`nullMatch` is set to `false`, where the individual's nationality is explicitly listed as `IQ`.

The second match is a new one with no specified nationality.

{% hint style="info" %}
By default, the API performs searches with the `nullMatch` option set to `true`, which means that it will return matches where the attribute associated with a search algorithm is not specified in the watchlists. This is the default behavior of the search API in the absence of the `nullMatch` option. To change this behavior, specify the value `false` for the `nullMatch` option when making a search query.
{% endhint %}


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