The topic of indication and its divisions has no precedence in Stoic-Megarian logic and it is regarded as logical innovations of Ibn Sina. On the whole he can be conceived more as the founder of the topic of indications and not its expositor.Among the threefold literal connotation, indication per nexum has been more controversial of the rest. Ibn Sina's statements and above all in the works of his commentators and followers there has been much controversies and doubts, as regards the nature, condition of actualization or even the Validity of this connotation.Doubt about non-independence of indication per nexum and its mixture of two corresponding connotation, doubt about rarity of connotation and interdiction of its applicability in the science because of non-infinity of its literal connotation have been among the most important of these doubts.This research, by emphasizing on the independence as well as literal mode of this connotation, tries to show that this connotation used in sciences, and regards the Validity of this connotation as "mental necessity" and of the kind of "necessity between absolute".

Extension agreement is a type of commitment where a party (or parties) to a contract undertake(s) to extend the contract for another term. These commitments are positive conditions as they are implied in another contract the subject of which is the conclusion of a legal deed. In addition, they are Contract promise as the parties undertake to conclude a contract in future. In practice, these commitments take different forms with varying Validity. In the event the extension is subject to the parties’ consent, or they are obligated to extend the contract without setting a consideration or a standard for it, extension shall be ineffective due to lack of intention and a clear object of contract. On the other hand, the duty implied by the parties as a condition identifies the consideration and counts as a Validity condition. However, the Validity of such duty which is set solely to determine a standard for consideration is the subject of much debate in Iranian Law, because the consideration is not specified at contract conclusion. The present paper proved that jurisprudential and legal foundations of the annulment of risky and uncertain transactions validate these conditions. Article 8 under Lessor-Lessee Act adopted in 1998 put an end to the debate and acknowledged their Validity. The author believes that judgment of the said article is among the general conditions of contracts.

One of the conditions for the Validity of a contract is that the contracting parties have the freedom to accept or reject it. For everything that is beyond the control of the will of one of the parties but forms a contract, two separate definitions are provided, including reluctance contract and emergency contract, according to which the Validity of the first one is conditional on the non-disclosure of the element of reluctance in it, but the second one is absolutely valid and enforceable from the point of view of the legislator. In these two cases, the reason for accepting the reluctance is personal circumstances. Whenever the insertion of coercion and reluctance in the contract is due to the obligation to comply with public interest, in this research it is called "compulsory contract" and it is divided into primary and secondary compulsory contract according to the stage of inclusion of the element of coercion into it. The research examines the Validity of such a contract, which is essentially a negation of the "principle of freedom”.

One of the most influential scientific approaches in the twentieth century has been discovering stem cells and their therapeutic effectiveness. On the one hand, countless diseases are considered incurable through valid scientific treatments and on the other hand, the hope for new treatments has been considered a promotor of the medical studies in research centers. Throughout such research pieces, the subject is the patient himself and since all available treatments have been futile for him, attempts are being made to treat him experimentally by implementing unconventional strategies, to see whether there might be a cure for him. The treatment contract is of great significance as it has been admitted as a joint connecting medicine and rights. In cases where the limits and extent of liability are disputed due to possible ambiguities of laws; basically, the heart of the legal relationship of medical professionals with their patients is the contract concluded between them. First, explaining the legal nature of the treatment contract and then using the selected contract's general and specific rules will be beneficial in this regard. Meantime, since stem cell research around the world is one of the new and unprecedented therapies and can have short-term and long-term side effects, a principled agreement between the medical team and human trials for medical research will eliminate any vaguenesses between both sides. Although adherence to medical criteria and ethical obligations are not embedded in the contracts' scope, it seems that the physician's liability, if the patient has referred to him with his consent, eliminates many of the problems between them and avoids possible legal disputes. Therefore, accurate knowledge of such a contract, both formally and substantively and conditions of its accuracy and Validity, seems inevitable.

The aim of the present study is to design a marketing model for nature tourism under sanction conditions. To evaluate the Validity of the nature tourism marketing model under sanctions, a quantitative research method was employed for data analysis, and the Smart PLS software was used to implement structural equation modeling (SEM). The statistical population consisted of employees of the Iranian Ministry of Cultural Heritage and Tourism, which spans 31 provinces and includes over three thousand permanent and contractual staff members. However, the sample was selected using conveniencesampling. Cochran's formula was used to determine the sample size, which was calculated to be 366 individuals. After extracting the questions, the questionnaire was distributed among the selected individuals and subsequently collected. Investigation of the relationships between variables: After evaluating the goodness-of-fit for the measurement models, the structural model, and the overall model—according to the data analysis algorithm in the PLS method—to confirm or reject the hypotheses, the t-value mustbe greater than 1. 96 or less than-1. 96. Values falling between these two thresholds indicate the absence of a statistically significant difference between the calculated regression weights and zero at the 95% confidence level. One of the essential and pivotal topics in tourism planning is determining the position of infrastructure and the current status of this sustainable industry in a given region. Achieving economic dynamism and prosperity in the country requires optimal utilization of infrastructure and identification of inequalities, making the regional stratification of nature tourism areas a necessity. By identifying and ranking infrastructure at the regional level, more effective management of tourists can be achieved

Trust contracts is an important issue that has always been disputed jurists and lawyers, nature, Validity and limits of liability clause is faithful. The nature of this condition can result if the condition is; It requires the fulfillment of certain causes and breath tradition to be achieved, In other words, the property with the consent of his faithful sponsor any loss or defect of the Trust's property, It is also possible for the condition is a verb; That is, if the property in trust by the trustee have wasted no abuse or wastage or defect, he is bound to compensate damages;But the credit condition of liability in contracts Trust (the loan) is disputed; but we must say that this requirement is contrary to the requirements of the contract itself and illegitimate and based on the principle of free will and is valid And its reliability to the extent that existing laws, public order and morality not in conflict. As with any provision of these conditions can In connection with the parties or in relation to third parties is concerned.

This article aims to review the book “, Noam Chomsky: nature and language”, , edited by Adriana Belletti and Luigi Rizzi. Despite all the ups and downs during the past seven decades, generative grammar is still recognized as the dominant language studies approach, particularly in North America. In the course of this book, first, a general outline of generative grammar is introduced. It follows by roots of the generative theory language, its prospects, and the challenges ahead. It then continues with an interview with Noam Chomsky done by the editors of the volume, raising critical issues about generative linguistics and the future of the theory. This article includes an overview of theoretical linguistics, emphasizing the evolution of generative grammar. Next, the structure and content of the book are examined, followed by an evaluation of the appearance and content. At the end of the article, the overall view on this book is concluded.

Take-or-Pay clause (T-o-P)، as an essential element of long-term off-take and supply contracts in energy sector، particularly in Gas Sales Agreements. The philosophy of T-o-P clause is based on the importance of the fact that the seller will receive a level of revenue guaranteed under the agreement that covers massive financial commitments and debts arising from the upstream project. Although T-o-P clause is frequently considered in GSAs، the Validity and applicability of this condition is subject to controversy among different legal systems. Some lawyers have treated this provision as a penalty clause which is invalid and unenforceable. However، others regard it as a valid and enforceable liquidated damage clause. This paper first focuses on uncertainties and ambiguities regarding the legal status of take-or-pay provision، particularly in English legal system. Then، it discusses the issue by considering the fundamentals of Islamic contract rules and jurisprudence، particularly Iranian legal system reflected in the Iranian Civil Code.