Planar roof truss grammar (seven-point symmetric variant)

A roof-truss grammar aligned to the seven-point symmetric loading formulation reported in the structural essay study.

See Grammar Problem Catalog for the grammar family index.

Quick Facts

Field	Value
Problem ID	`planar_roof_truss_seven_point_symmetric`
Problem Family	grammar
Implementation	`design_research_problems.problems.grammar._planar_truss:PlanarTrussSpanProblem`
Capabilities	`discrete-actions`, `external-adapter`, `optional-evaluator`, `serializable-state`, `statement-markdown`
Study Suitability	none
Tags	`grammar`, `truss`, `roof`, `discrete`, `topology`, `symmetric`

Taxonomy

Formulation: discrete_grammar
Convexity: not_applicable
Design Variable Type: discrete
Is Dynamic: no
Orientation: engineering_practical
Feasibility Ratio Hint: 0.25
Objective Mode: single
Constraint Nature: hard
Bounds Summary: symmetric planar roof-truss topology with seven fixed roof load points
Tags: grammar, truss, roof, discrete, topology, symmetric

Statement

This catalog entry approximates the sixth planar roof-truss formulation from the structural essay study: seven uniformly spaced fixed roof load points with left-right symmetry enforced.

The state begins with pinned and roller supports plus seven loaded roof joints. Interior joints and members are edited through mirrored actions so the topology remains symmetric about the roof apex.

Problem Shape

Field	Value
State Type	PlanarTrussState
Initial Transition Count	23
Initial Rule Names	`add_joint`, `add_joint_pair`, `add_member`

Manifest Parameters

Key	Value
candidate_point_fractions	[[0.18, 0.2], [0.34, 0.32], [0.5, 0.2]]
enforce_symmetry	yes
load_magnitude	1000
max_height	2.5
roof_load_x_fractions	[0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875]
span	10

Initial Transition Summary

Rule Name	Transition Count
add_joint	1
add_joint_pair	2
add_member	20

Library Interface

initial_state()
enumerate_transitions(state)
enumerate_next_states(state)
evaluate(state)