DB RelationalAlgebra vs Dolgate

A native iPad and iPhone app that converts a SQL query typed, pasted, or imported from a .sql file into relational algebra, tuple relational calculus and domain relational calculus. Each notation gets a step by step derivation, a final oneline formula, and an interactive diagram an operator tree for the algebra, a quantifier scope tree for the calculus and a fourth view stacks all three against the same query. Whatever SQL asks for that a notation cannot express exactly is reported rather than quietly approximated.

A remote access client you use across desktop and mobile. Hosts and sessions sync between them, and your connection details stay under your control. • Connect — SSH shell, SFTP file transfer, and RDP and VNC remote desktops. Password and private key authentication, with jump hosts. • Networking — Reach hosts inside a Tailscale tailnet, and AWS EC2 instances over SSM. No public IP and no open inbound port required. • Sync — The hosts and groups you add are the same on desktop and mobile. Change devices and there is nothing to set up again. • End-to-end encryption (zero-knowledge) — The encryption key is derived from your sync passphrase. The server never holds the plaintext key, so it cannot read your hosts or credentials. • Local-first and private — Passwords and private keys are stored in the iOS Keychain. No telemetry, no analytics, no ads. You can delete your account and your data from inside the app. Use the default sync server, or self-host the open-source server to keep your data on your own infrastructure.