ToolJovia
Education

Forward Propositional Derivation Checker

Check explicit local inference steps and their earlier-line references without treating a plausible conclusion as a proof.

✓ Browser-local processing
Processed in this tab. Up to 100,000 characters unless this tool states a smaller limit.

Loading tool…

How to use Forward Propositional Derivation Checker

Review a bounded forward derivation from user-declared premises. Invalid steps cannot justify later lines, while premise identity, structural formulas, and the distinction between a derived goal and a valid complete submission remain visible.

  1. Enter input, premise formulas json, goal formula.
  2. Choose the settings for forward propositional derivation checker, then run the tool.
  3. Review the result and any limitations before copying or downloading it.

Good to know

  • 50 premises, 300 steps, 500 characters per formula and the existing bounded Boolean grammar with structural depth at most 30. A browser module worker has a 2-second compute deadline after startup.
  • Rules: premise, reiterate, and-intro/left/right, modus-ponens/tollens, or-left/right, double-negation-intro/elim and iff-left/right/intro. References are ordered and 1-based. No temporary assumptions, subproof discharge, predicate logic or automated proof search.
  • Processing is local. Output is limited to 1,000,000 text characters unless a stricter file limit is stated.

Common questions

Can a correct goal excuse an invalid line?

No. The report separates whether the goal appears on a valid line, whether the final line matches it, and whether every submitted step is justified. References to invalid lines are refused as proof evidence.

Is this input sent to a server?

No. The application processes this input inside your browser tab and does not save it to persistent storage.

Keep going with related tools

All education →
Education

Boolean Truth Table Workbench

Enumerate bounded propositional truth tables and find real counterexamples to formula equivalence.

Education

FIRST, FOLLOW and LL(1) Table Workbench

Compute nullable symbols, FIRST/FOLLOW sets and real predictive-table conflicts for your explicit token grammar.

Education

Explicit Epsilon-NFA Workbench

Simulate finite token strings or build a reachable deterministic transition table from a supplied epsilon-NFA.

Education

Small Boolean Minimization Workbench

Turn a small 0/1/X output specification into a minimum-literal two-level Boolean form with complete truth-row witnesses.