Tu Vi Dau So (Tử Vi Đẩu Số)

Vietnam's Chart of Destiny — the Purple Star, in Its Own Tongue

Overview

Ask a Vietnamese family about fate and the answer is a lá số Tử Vi — the chart of the Purple Star. Tử Vi Đẩu Số is Vietnam's dominant natal art: the same twelve-palace architecture as Chinese 紫微斗數, carried south centuries ago and so thoroughly naturalized that every star, palace and cục speaks Vietnamese — Tử Vi and Thiên Cơ, Mệnh and Phu Thê, Thủy Nhị Cục. And Vietnamese practice adds an emphasis the Chinese schools rarely match: the two great voids. Tuần, the year's uncovered pair of branches, and Triệt, the cutting emptiness fixed by the year stem, are treated by Vietnamese readers as decisive — a brilliant palace under Triệt is a promise interrupted. askTIAN serves the full lá số: the verified Purple Star engine underneath, complete Sino-Vietnamese nomenclature on top, and Tuần/Triệt computed by their classical rules and flagged on every palace they touch.

Origin & history

Tử Vi entered Vietnam with the broader Sino-Vietnamese scholarly inheritance and became the court and village art of destiny reading — legend ties its systematization to the Trần-dynasty scholar Trần Đoàn (the Vietnamese rendering of Chen Tuan, the semi-legendary Daoist credited with the Chinese system too). The names are the standard Sino-Vietnamese readings of the classical characters: 紫微 read as Tử Vi, 天府 as Thiên Phủ, 化祿 as Hóa Lộc — a complete, regular sound-mapping that lets a Vietnamese lá số and a Chinese 命盤 describe the identical sky in different tongues. What diverged is emphasis: the Vietnamese tradition elevated Tuần Trung Không Vong and Triệt Lộ Không Vong — both classical Chinese voids — into first-rank chart features, printed boldly across palace boundaries on every traditional lá số.

askTIAN ships Tử Vi the honest way: the chart mathematics is the catalogue's existing, test-locked ZWDS engine — lunar conversion, Mệnh and Thân, the cục, all fourteen majors with brightness, the auxiliary roster, the Tứ Hóa resolved to palaces, decade luck — and the Vietnamese layer adds naming and the voids without touching a single computed value (chart-consistency tests prove palace-for-palace, star-for-star identity with the engine). Tuần is computed by the same xunKong helper the BaZi day engine verifies; Triệt by the five fixed stem-pairs of the classical rule, all locked as tests. A live-chart sweep test guarantees no star the engine can place ever appears without its Vietnamese name. Disclosed plainly: minor-star placement variants between Vietnamese lineages exist beneath the mainstream conventions this engine follows, and the decisive interpretive weight of the voids is the tradition's claim, served as tradition.

How it works

Give the engine a birth date, hour and gender. The shared Purple Star engine converts to the lunar calendar, seats the Mệnh and Thân palaces, determines the cục, places the fourteen major stars with brightness and the auxiliary stars, resolves the four transformations, and lays out the twelve palaces with their decade spans. The Vietnamese layer then renders everything bilingually — each star and palace carrying both its Vietnamese and Chinese name — computes Tuần from the lunar year pillar's xun (the two branches its decade leaves uncovered) and Triệt from the year stem's fixed pair, flags every palace sitting in either void, and states each rule in the response. The result is a complete lá số payload: Mệnh and Thân with their rulers, the cục, the Tứ Hóa under their Hóa names with host palaces, twelve fully-localized palaces with void flags and decades, and a method string that says exactly which layer computed what.

Good for

• Serving Vietnamese-speaking users their own chart in their own nomenclature
• The Tuần/Triệt overlay — the void markers every traditional lá số prints in bold
• Bilingual rendering: every star and palace carries vi + zh for cross-tradition apps
• A verified-engine foundation: the Vietnamese layer provably alters no computed value
• Pairing with ziwei.chart to show one sky under two traditions
• The catalogue's first Vietnamese system — a new tradition tag for filtering
• Decade luck, Tứ Hóa and brightness — the full chart, not a simplified export

Use cases

The Lá Số Renderer

One call returns everything a traditional Vietnamese chart sheet shows — twelve palaces in Vietnamese, stars with brightness, Tuần and Triệt striped across their branch pairs — ready to draw in the classic grid.

The Void Reading

Surface which palaces sit under Tuần or Triệt with the rules quoted — the feature Vietnamese readers check first, computed classically instead of copied from a table image.

The Two-Traditions View

Render tuvi.chart beside ziwei.chart: identical mathematics, two nomenclatures — a demonstration of how a tradition travels that only a shared verified engine can make honest.

The Diaspora Product

Vietnamese communities worldwide keep the lá số tradition alive; serve them charts in the names their grandparents used, with the engine's accuracy culture underneath.

Key terms

Lá Số

The chart sheet — the twelve-palace grid a Tử Vi reading is drawn on.

Mệnh / Thân

The Life and Body palaces — the chart's anchors, each with its ruler star (chủ tinh).

Tuần Trung Không Vong

The year pillar's xun voids — the two branches its sexagenary decade leaves uncovered; palaces there sit 'within the Tuần'. Computed by the verified xunKong helper.

Triệt Lộ Không Vong

The cutting void — two branches fixed by the year stem (Giáp/Kỷ→Thân·Dậu … Mậu/Quý→Tý·Sửu), the classical 截路空亡 rule, all five pairs test-locked.

Cục

The bureau (Thủy Nhị, Mộc Tam, Kim Tứ, Thổ Ngũ, Hỏa Lục) that sets the Tử Vi star's placement and the decade rhythm.

Tứ Hóa

The four transformations — Hóa Lộc, Hóa Quyền, Hóa Khoa, Hóa Kỵ — resolved to their host stars and palaces, localized.

The Fourteen Majors

Tử Vi through Phá Quân — the principal stars, each with brightness, under their standard Sino-Vietnamese readings.

Lineage Variants

Vietnamese schools differ on some minor-star placements beneath the mainstream conventions this engine follows — disclosed, never silently chosen.

API

The askTIAN Tử Vi API serves Vietnam's national natal art on the catalogue's verified Purple Star engine: complete Sino-Vietnamese nomenclature (a live-chart sweep test guarantees no star lacks its Vietnamese name), Tuần computed by the verified xunKong helper and Triệt by the classical five stem-pairs (all locked as tests), every palace flagged for both voids with the rules stated, and chart-consistency tests proving the Vietnamese layer alters no computed value. Bilingual throughout, decade luck and Tứ Hóa included. Pure compute, no LLM, 8 TIAN.

Endpoint: POST /trpc/tuvi.chart — 8 TIAN Points. See the API documentation and Playground.