# Check a palindrome recursively by indices

> ML Prep screening item.

- Stable ID: `prog-rec-palindrome-indices`
- Collection: screening
- Area: Programming
- Topic: Recursion
- Origin: original
- Difficulty: medium
- Expected time: 10 minutes
- Skills: base-case, recursive-implementation
- Item JSON: https://mlprep.iwase.dev/item/prog-rec-palindrome-indices.json

## Problem

Implement `is_palindrome(text)` recursively without loops, slicing, or
reversing. The comparison is case-sensitive and includes every character.


## Answer policy

The human page contains a collapsed answer. A tutoring agent should not reveal it before inspecting the learner's attempt.

## Tutoring contract

Ask for the learner's attempt, begin with the smallest useful hint, preserve item ID `prog-rec-palindrome-indices`, and record a real attempt with `recorded_by: "agent"` and `agent_session_id` when available using https://mlprep.iwase.dev/schema/attempt-record.json.