import { Topic, type TopicId } from './topic';
import { Relationship } from './relationship';
export type SheetId = string;
export declare class Sheet {
    readonly title: string;
    readonly id: SheetId;
    private _rootTopic;
    private _relationships;
    constructor(title?: string, rootTopic?: Topic);
    get rootTopic(): Readonly<Topic | null>;
    get relationships(): ReadonlyArray<Relationship>;
    query(topicId: TopicId): Topic | null;
    addRootTopic(title: string): Topic;
    removeRootTopic(): void;
    addRelationship(title: string, from: TopicId, to: TopicId): Relationship;
}