# Automatic Checking of Your Own Solutions

**4f Checker **allows you to check if your derivation is mathematically correct online. The checker formulates each step in the derivation as a mathematical theorem, and sends the theorem to an automatic theorem prover that runs in the cloud. The derivation is correct, if each step in the derivation is proved correct. The checker warns for each derivation step that it was not able to prove correct.

The automatic checking function can be used everywhere where the eMath editor is used: in textbooks when solving assignments, in notebooks and in course books. The checker requires an active internet connection. Check our Products & Pricing page for the best way for you to use the checker.

### Example Derivation with an Error

The derivation below contains an error, the second derivation step is not correct. The checker shows a "!" as a warning sign for the incorrect step, and a check mark for the correct ones.

### Corrected Derivation

Here we have corrected the erroneous step. The checker now marks each step as correct, so the whole derivation is correct.

### Automatic Checking, Basic

### Automatic Checking, More Advanced

### A Personal Digital Tutor

Thinking of hiring a tutor for your high school student? Success in High School opens many doors to future colleges and universities. It also affects your child's self esteem. We hear it a lot from adults, "I know I am not bad at math, but somehow I just missed a few things and never really got it..." In math, missing one point will make the rest very difficult to understand. Getting a little extra help exactly where it is needed will make all the difference for your child's future math studies. But tutors are expensive, so how about an e-tutor?

### Fixing the Broken Feedback Loop

The feedback loop in today’s math education is broken: students work on their math problems, but don’t get proper feedback on their own solutions. Rather, they are shown model solutions in class, and are supposed to spot the errors in their own solutions from these. Some can do this, but many will fail and keep repeating the same errors in subsequent homework, until they drop out because they just don’t get it. Teachers could help, but there is no time to give individual feedback and tutoring to all students in the class.

### How the Checker Works

You check a derivation by choosing "check" in the checker menu. This will start the process of checking. The checker will return a mark for each step in the derivation, in the right hand side column. The checker may run into different situations when checking the step:

**Syntax error (red x-mark): **The checker does not understand the derivation step . There could be a syntax error in the step, a missing declaration, or you may be using mathematical notation that the checker does not know. You need to rewrite the step.

**Step is correct (green V-mark).: **The checker may report that the step is correct Then you are fine.

**Warning (red !-mark)**: The checker may report that it was not able to prove the step (red exclamation mark).

### What does a warning mean

A checker warning (red ! -mark) can mean different things:

**Step is incorrect: **The step cannot be proved because it is incorrect. You need to fix the error.

**Run out of time: **The checker does not find a proof within the alloted time slot. If you still believe that the step is correct, you could try to help the checker by splitting the step up into smaller steps.

**Incomplete information: **The checker does not know enough about the underlying mathematics to prove the step. Try to add assumptions, facts, or definitions that could make it easier for the checker to prove the step.