Z3-solver installed in Python 3 (Spyder editor), but cannot import everywhere

Question

I have tried to install the Z3 theorem solver (https://github.com/Z3Prover/z3). I can run the example file that comes in the release version z3-4.12.4. The file is found in "..\z3-4.12.4-x64-win\bin\python", and is shown below:

from z3 import *

x = Real('x')
y = Real('y')
s = Solver()
s.add(x + y > 5, x > 1, y > 1)
print(s.check())
print(s.model())

If I try to run this example code from a different location, then I get the following error:

ModuleNotFoundError: No module named 'z3'

Below the relevant details about the platform I am using the installation steps I have taken so far:

Platform:

• I am using Windows-11 64 bit.
• I am using Python 3.12.1
• I am using the Spyder editor to write my codes.

Installation steps:

• I went to https://github.com/Z3Prover/z3/releases/tag/z3-4.12.4 and downloaded the file "z3-4.12.4-x64-win".
• Extracted the file "z3-4.12.4-x64-win" and placed it in "C:\Users\name\AppData\Local\Programs\Python\Python312\Lib\site-packages".
• Added to the "Path" environement variable the following location "C:\Users\name\AppData\Local\Programs\Python\Python312\Lib\site-packages\z3-4.12.4-x64-win\bin".
• Created another environmental variable called "PYTHONPATH", and added the following location "C:\Users\name\AppData\Local\Programs\Python\Python312\Lib\site-packages\z3-4.12.4-x64-win\bin\python".

At this point I expected things to work, but I still kept getting the error shown above. I have also tried to install z3-solver using pip, but this made no difference to my problems.

Answer 1

In my configuration, the variables are:

path = Z:\Tools\Python38;Z:\Tools\z3-4.12.2-x64-win\bin
pythonpath = Z:\Tools\z3-4.12.2-x64-win\bin\python

I have not copied the Z3 python files to site-packages but rather left them in their Z3 installation directory and adjusted pythonpath accordingly.

Answer 2

I have managed to solve the problem.

I found out that if I ran python through PowerShell (alternatively use Command Prompt), then I was able to import the z3 module without any issues. This told me that the issue was rather that Spyder was unable to find the z3 module.

Following the advice from Norberto, it seemed that all I had to do is go in my Spyder editor, and in Tools>Pythonpath manager add the path to where I had saved the z3 module.

Unfortunately I then received the following error: "This directory cannot be added to PATH. If you want to set a different Python interpreter, please go to Preferences > Main Interpreter". This error was also discussed in this post.

In that post, I saw the comment of uninstalling Spyder, and installing it again through conda. This website explains how to do this, where after uninstalling Spyder, the next step is to install miniconda.

Unfortunately once again, while in website conda is then a recognised command, that was not my case. This again is a common issue, which was covered in the following post. The answer from Raja Ram T was helpful to solve that problem.

Once I had finally resolved my conda problems, I was able to go back to follow the advice from this website, and once completed, I had finally resolved this issue.

I hope this helps to anyone else who has encountered the same difficulties. I would also look forward for any improved alternatives, given that I have little understanding of all of this.