islpy

2026.1 verified Mon Apr 27 auth: no python

Python wrapper around the Integer Set Library (isl), providing operations on integer sets, relations, and affine constraints. Current version 2026.1, released on a rolling basis with no fixed cadence.

pip install islpy

Common errors

error ModuleNotFoundError: No module named 'islpy' ↓

cause islpy not installed in the current Python environment.

fix

Run: pip install islpy

error ValueError: could not create isl_basic_set: invalid input ↓

cause The string representation for a set or relation is malformed.

fix

Ensure the string follows isl syntax. For example: '{ [x] : x >= 0 }' or '[n] -> { [x] : x <= n }'.

Warnings

breaking Python 3.10 minimum required; islpy dropped support for Python <3.10 in version 2024.x. Attempting to install on older Python will fail. ↓

fix Upgrade to Python 3.10 or later.

gotcha String-based set representation uses isl's syntax, which can be confusing. Misplacing brackets or missing dimensions leads to errors. ↓

fix Use islpy parsing helpers like isl.BasicSet.read_from_str or carefully double-check syntax.

Imports

islpy
```
import islpy
```
Direct import is the standard and only supported pattern.

Quickstart

Basic usage showing creation of integer sets and intersection.

import islpy as isl

# Create a basic set: all integer pairs (x, y) with x + y <= 5
s1 = isl.BasicSet('[n] -> { [x, y] : x + y <= n }')
print(s1)

# Create a second set
s2 = isl.BasicSet('[n] -> { [x, y] : x >= 0 and y >= 0 }')

# Intersection
intersection = s1.intersect(s2)
print(intersection)

# Check if non-empty
print(f"Is empty? {intersection.is_empty()}")