added calendar-arithmetic tasks

GALLERY.md

@@ -255,6 +255,32 @@ Metadata: {'rotation': 17, 'cipher_text': 'ZW PFLI JKFDRTY ZJ FLK FW ZK DLJK SV
 
 ````
 
+### calendar_arithmetic
+Generates various calendar arithmetic tasks
+Default configuration:
+```python
+year = 2024
+tasks = None
+seed = 42
+size = 500
+```
+
+Example tasks:
+```
+Example 1:
+Question: How many business days (Monday-Friday) are there from Tuesday, December 17, 2024 to Sunday, December 29, 2024 (inclusive of both dates)? Give the count numerically.
+Answer: 9
+Metadata: {'task': 'count_business_days', 'start_date': '2024-12-17', 'end_date': '2024-12-29'}
+Example 2:
+Question: Given that January 1 fell on a Sunday, which weekday occurs on August 17? State the weekday (Monday through Sunday).
+Answer: Friday
+Metadata: {'task': 'first_day_of_year', 'year': 2024, 'first_day': 'Sunday', 'target_date': '2024-08-17', 'delta_days': 229}
+Example 3:
+Question: In August 2024, if an event recurs on the first Tuesday, what is the date (day of the month) of the event? Answer with a number. Answer with -1 if the ordinal does not exist in the month.
+Answer: 6
+Metadata: {'task': 'recurring_event_day', 'year': 2024, 'month': 8, 'ordinal': 'first', 'weekday': 'Tuesday'}
+```
+
 ### chain_sum
 Generates simple arithmetic tasks using only + and - operators
 

README.md

@@ -76,6 +76,7 @@ See the [Dataset Gallery](GALLERY.md) for a complete list of available datasets
 ### <small>Arithmetic Tasks</small>
 
 - `BasicArithmeticDataset`: Generate arithmetic expressions with configurable complexity and operators (+, -, \*, /)
+- `CalendarArithmeticDatset`: Generate arithmetic problems around calendar navigation logic
 - `ChainSum`: Generate addition/subtraction chains with configurable length and digit counts
 - `FractionSimplificationDataset`: Generate fraction simplification tasks with configurable complexity
 - `GCDDataset`: Generate Greatest Common Divisor problems with configurable number of integers

reasoning_gym/arithmetic/__init__.py

@@ -15,13 +15,18 @@
 from .leg_counting import LegCountingConfig, LegCountingDataset
 from .prime_factorization import PrimeFactorizationConfig, PrimeFactorizationDataset
 from .time_intervals import TimeIntervalsConfig, TimeIntervalsDataset
+from .calendar_arithmetic import CalendarArithmeticConfig, CalendarArithmeticDataset
 
 __all__ = [
     "BasicArithmeticDataset",
     "BasicArithmeticDatasetConfig",
     "basic_arithmetic_dataset",
     "ChainSum",
     "ChainSumConfig",
+    "CalendarArithmeticConfig",
+    "CalendarArithmeticDataset",
+    "Weekday",
+    "CalendarTask",
     "FractionSimplificationConfig",
     "FractionSimplificationDataset",
     "GCDConfig",